IX Physics Solved Numerical Floating bodies ( Gra...

CBSE Physics: 9th Physics Solved Numerical Floating bodies

Q. a cube of mass 1kg with each side of 1cm is lying on the table. find the pressure exerted by the block on the table. take g=10 m/s²

Ans: Pressure is given as force/area so, Force, F = mg = 1000 X 981 gm.m/s²

and area, A = 1x1 cm² = 1 cm²

Thus, the pressure exerted would be P = (981 X 1000) / 1 or P = 9.81 X 10 ⁵ pa

Q. The mass of a solid iron cube of side 3cm is to be determined usig a spring balance. If the of iron is approximately 8.5 g/cm³, the best suited spring balance for determining weight of the solid would be of

1. range 0-250gwt ; least count 1gwt 2. range 0-250gwt ; least count 5gwt

3. range 0-1000gwt ; least count 5gwt 4. range 0-1000gwt ; least count 10gwt

Ans: Edge=3 cm , Density=8.5 g/cm³

Mass= density x volume = 8.5 x(3x3)=229.5gwt

Therefore second spring balance of range 0-250 gwt with least count 5gwt will be suitable.

Q. The density of turpentine oil is 840 Kg/ m3. What will be its relative density. (Density of water at 4 degree C is 10 cube kg minus cube)

Ans:

Relative Density = Density of Substance/ Density of water at 4 0c

Density of turpentine oil = 840 kg/ m3 ( given).

Density of water at 4 0c = 1000 kg/ m3

Relative density of turpentine oil = Density of turpentine oil / Density of water at 4 0c

= (840 / 1000 ) kg m-3/ kg m-3 = 0.84

Since, the relative density of the turpentine oil is less than 1, therefore it will float in water.

Q. A solid body of mass 150 g and volume 250cm3 is put in water . will following substance float or sink if the density of water is 1 gm-3?

Ans: The substance will float if its density is less than water and will sink if its greater.

so, density of solid body is d = mass/volume

or d = 150/250 = 0.6 gm/cm3 which is less than the density of water (1 gm/3).

So, the solid body will float on water.

Q. A body weighs 50 N in air and when immersed in water it weighs only 40 N. Find its relative density.

Ans: the relative density would be ratio of the density of the body with respect to air and the density of the body with respect to water.

so, F1 = 50 N F2 = 40 N

so, F1/F2 = 50/40 or relative masses m1/m2 = 5/4 and

density = mass/volume and as volume remains constant,

Relative density = d1/d2 = 5/4

Q. A ball of relative density 0.8 falls into water from a height of 2m. find the depth to which the ball will sink ?

Ans: Speed of the ball

V = Ö2gh = Ö 2x10x2 = 6.32 m/s

Buoyancy force by water try to stop the ball.

Buoyancy force = weight of displaced water = dx Vxg

where d = density of water V = volume of the ball , g = 10 m/s²

deceleration of the body by buoyancy force, a = (dVg)/ m

where m= d'V d' = density of block

a = dVg/(d' V) = dg/d' =(d/d')*g =g/(0.8)= 10/0.8 (Given, d'/d = 0.8)= 12.5 m/s²

Net deceleration of ball,a' = a-g = 2.5 m/s²

Final speed of ball v' = 0 Use v' ² = v² + 2a's s= depth of ball in the water

=> 40 = 0 + 2x2.5xs => s = 8m

Q. Equal masses of water and a liquid of relative density 2 are mixed together. Then, the mixture has a relative density of (in g/cm³) a)2/3 b)4/3 c)3/2 d)3

Ans: he masses of two liquids are equal, let it be m.

Let the relative densities of water and liquid be ρ₁ and ρ₂ respectively.

The volume of the two be V₁ and V₂, of water and liquid respectively.

The volume of the mixture would be, V = V₁ + V₂ (1)

also, volume = mass/density

thus,

2m/ρ (V) = m/ρ₁ (V ₁ ) + m/ρ₂ (V ₂ )

here ρ₁ = 1,ρ₂ = 2 and ρ is the relative density of the mixture.

now,

2/ρ = 1/ρ₁ + 1/ρ₂

by substituting the values, we

ρ/2 = 2/3

or, the relative density of the combined liquid will be, ρ=4/3

9th ASSIGNMENT FOR THE SESSION 2011-2012 Science and technology

CBSE PHYSICS: ASSIGNMENT FOR THE SESSION 2011-2012 Class: IX Sub...

JSUNIL TUTORIAL: Section A : Physics
Q.1. Define work energy and power. Give the proper SI units. Hence derive the expression for kinetic and potential energy.
Q.2. State and prove the principle of conservation of energy. Also prove work energy theorem.
Q.3. A boy is moving on a road against a frictional force of 5N. After travelling a distance of 1.5km,he forgot the correct path at a roundabout (figure) of radius 100m. However he moves on a circular path for one and half cycle and then he moves forward upto 2 km. Calculate the workdone by him.
Q.4. Weight of a wooden piece is 6 kg.While floating in water its 1/3 rd volume remains submerged in
water. Calculate the maximum weight that may be placed on it so that it may float completely submerged.
Q.5. When a boat floats in water its one fourth volume remains submerged. The maximum weight that can be placed on boat is 1200 kgf. Calculate the weight of empty boat.
Q.6. Explain the working and application of a SONAR. How defects in ametal block can be dected using ultrasound.
Q.7. A stone is dropped from the top of a tower 500m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g=10m/s2 and speed of sound =340m/s.
Section B : Chemistry
1. Calculate the mass of : a) 0.5 mole of silver b) 0.5 mole of sugar (C12H22O11). (Given atomic
masses are Ag = 108, C = 12, O = 16, H = 1)
2. Calculate the a) the number of atoms in one gram of gold b) the number of molecules in a drop of water weighing 0.05g.(atomic mass of gold = 197u) 1 x 10²² atoms of an element X are found to have a mass of 930mg. Calculate the molar mass of the element X.
3. What is the difference between the atomic mass and gram atomic mass of an element?
4. What are the limitations of Dalton’s atomic model?
5. What are the draw backs of Rutherford’s atomic model?
6. What are the salient features of Bohr’s atomic model?
7. What are the postulates of Dalton’s modified atomic theory?
8. Write the electronic configuration of the isotopes of chlorine and isobars of Ar, Ca.
9. The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes of oxygen 16 and 18 in the sample?
10. A Bromine atom is available in the form of two isotopes. 79Br (49.7%) and 81Br (50.3%). Calculate the average atomic mass of Bromine atom. The atomic no. of Bromine is 35.
11. No. of protons, neutrons and electrons in four spaces A, B, X and Y are respectively 6, 6, 6; 7, 7,7; 6, 8, 6; and 9, 10, 10. Give symbolic representation of each species and tell which of them are isotopes and which are isobars.
12. What do you mean by radio isotopes? Give two applications of isotopes.

13. Differentiate between isotopes and isobars. Write the application of the following isotopes:
a) U-235, Co-60, P-32 and I-131.
14. Atomic no. of Na is 11 and mass no. is 23. What type of ion will be formed by it and how will you represent it? Calculate the no. of electrons, neutrons and protons in the ion formed.
15. An ion X-2 contains ten electrons and 8 neutrons. What are the atomic no. and mass no. of element X? Name the element.
Section C : Biology
CHAPTERS - BIOLOGICAL DIVERSITY, HEALTH & DISEASES, OUR ENVIRONMENT
(BIOGEOCHEMICAL CYCLES, GREENHOUSE EFFECT)
1. What is evolution? How is algae different from fungi? Draw diagram of any one member of Protista.
2. How are pteridophytes different from bryophytes? Write any four differences between angiosperms and gymnosperms.
3. Write the differences (any four) between the following groups a) poriferans and coelenterates b) molluscs and arthropods c) flatworms and roundworms d) aves and mammals
4. Explain the different means by which infectious diseases spread in the environment? List the preventive measures of such diseases.
5. Justify, why it is difficult to make antiviral medicines than antibacterial medicines.
6. Explain the different processes involved in oxygen and water cycle operating in nature.
7. Represent schematically the carbon and nitrogen cycle operating in the biosphere. How is carbondioxidefixed in environment?

ASSIGNMENT FOR THE SESSION 2011-2012 Class: IX Subject : Science & Technology

JSUNIL TUTORIAL: Section A : Physics 
Q.1. Define work energy and power. Give the proper SI units. Hence derive the expression for kinetic
and potential energy.
Q.2. State and prove the principle of conservation of energy. Also prove work energy theorem.
Q.3. A boy is moving on a road against a frictional force of 5N. After travelling a distance of 1.5km,he forgot the correct path at a roundabout (figure) of radius 100m. However he moves on a circular path for one and half cycle and then he moves forward upto 2 km. Calculate the workdone by him.
Q.4. Weight of a wooden piece is 6 kg.While floating in water its 1/3 rd volume remains submerged in
water. Calculate the maximum weight that may be placed on it so that it may float completely submerged.
Q.5. When a boat floats in water its one fourth volume remains submerged. The maximum weight that can be placed on boat is 1200 kgf. Calculate the weight of empty boat.
Q.6. Explain the working and application of a SONAR. How defects in ametal block can be dected using ultrasound.
Q.7. A stone is dropped from the top of a tower 500m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g=10m/s2 and speed of sound =340m/s.
Section B : Chemistry
1. Calculate the mass of : a) 0.5 mole of silver  b)  0.5 mole of sugar (C12H22O11). (Given atomic
masses are Ag = 108, C = 12, O = 16, H = 1)
2. Calculate the a) the number of atoms in one gram of gold    b) the number of molecules in a drop of water weighing 0.05g.(atomic mass of gold = 197u) 1 x 10²² atoms of an element X are found to have a mass of 930mg. Calculate the molar mass of the element X.
3. What is the difference between the atomic mass and gram atomic mass of an element?
4. What are the limitations of Dalton’s atomic model?
5. What are the draw backs of Rutherford’s atomic model?
6. What are the salient features of Bohr’s atomic model?
7. What are the postulates of Dalton’s modified atomic theory?
8. Write the electronic configuration of the isotopes of chlorine and isobars of Ar, Ca.
9. The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of  isotopes of oxygen 16 and 18 in the sample?
10. A Bromine atom is available in the form of two  isotopes. 79Br (49.7%) and 81Br (50.3%). Calculate the average atomic mass of Bromine atom. The atomic no. of Bromine is 35.
11. No. of protons, neutrons and electrons in four spaces A, B, X and Y are respectively 6, 6, 6; 7, 7,7; 6, 8, 6; and 9, 10, 10. Give symbolic representation of each species and tell which of them are isotopes and which are isobars.
12. What do you mean by radio isotopes? Give two applications of isotopes. 13. Differentiate between isotopes and isobars. Write the application of the following isotopes:
a)  U-235, Co-60, P-32 and I-131.
14. Atomic no. of Na is 11 and mass no. is 23. What type of ion will be formed by it and how will you represent it? Calculate the no. of electrons, neutrons and protons in the ion formed.
15. An ion X-2  contains ten electrons and 8 neutrons. What are the atomic no. and mass no. of element X? Name the element.
Section C : Biology 
CHAPTERS - BIOLOGICAL DIVERSITY, HEALTH & DISEASES, OUR ENVIRONMENT 
(BIOGEOCHEMICAL CYCLES, GREENHOUSE EFFECT) 
1. What is evolution? How is algae different from fungi? Draw diagram of any one member of Protista.
2. How are pteridophytes different from bryophytes? Write any four differences between angiosperms and gymnosperms.
3. Write the differences (any four) between the following groups
 a) poriferans and coelenterates   b) molluscs and arthropods  c) flatworms and roundworms   d) aves and mammals
4. Explain the different means by which infectious  diseases spread in the environment? List the preventive measures of such diseases.
5. Justify, why it is difficult to make antiviral medicines than antibacterial medicines.
6. Explain the different processes involved in oxygen and water cycle operating in nature.
7. Represent schematically the carbon and nitrogen  cycle operating in the biosphere. How is carbondioxidefixed in environment?

CBSE Sample paper science class 9th SA2 solved

CBSE ADDA: sample paper science class 9th sa2 solved:

1. Relative density of silver is 10.8. The density of water is 10³ Kgm^-3. What is the density of silver in SI unit?

Ans: Relative density of silver = 10.8 Relative density of water = 10³ Kgm^-3

Density of silver = Relative density of silver x Relative density of water = 10.8 x 10³ Kgm^-3

2. Is potential energy a vector or a scalar quantity?

Ans: Potential energy is a scalar quantity.

3. (i) Give any two examples of longitudinal waves.(ii) What is the most essential property of a wave motion and why?

Ans: (a) i. Waves produced in air. ii. When a freely suspended spring is pulled downwards and released, longitudinal waves are produced.

(b) The most essential property of a wave motion is its frequency. Frequency of a wave is its inherent characteristic and does not change by the change in temperature, pressure or change in medium.

full paper

CBSE Physics IX Physics Summative II Worksheet – 2011-12

CBSE Physics IX Physics Summative II Worksheet – 2011-12 JSUNIL TUTORIAL,SAMASTIPUR

1 MARK QUESTIONS

1. Nails and pins have pointed tips. Give reasons?

2. State Archimedes’ principle.

3. What will happen to the amount of work done if (a) the magnitude of force applied is increased. (b) the displacement of the body is reduced?

4. What is the work done on a body moving in a circular path?

5. Convert kwh into joules.

6. Why are sound waves called mechanical waves?

7. We cannot hear sound from the space. Why?

8. Why can we recognize our family members from their voice without seeing them?

9. What is meant by echocardiography?

10. What is the audible range of human ear?


2 MARK QUESTIONS

1. What is meant by reverberation? That are the measures taken to reduce reverberation?

2. Distinguish between longitudinal waves and transverse waves?

3. What happens to the kinetic energy of a body if the mass and velocity of the body are doubled?

4. When is the work done by a force in a body said to be negative? Give two examples.

5. A thrust of 200N exerts a pressure of 10Pa on a body. Calculate the area on which the pressure is exerted?

6. What is meant by echo? What are the conditions for the formation of an echo?

7. 8000 J of work is done by a machine to lift a mass of 100kg vertically upwards. Calculate the height to which the mass is lifted?

8. State the essential conditions needed for work to be done?

9. Derive the formula for gravitational potential energy.

10. Give the sequence of energy changes taking place in the production of electricity from a dam ?

3 MARKS QUESTIONS
1. An object of mass 80g has a volume of 20cm3. Will the object float on the water? Why? What will be the mass of water displaced by the object?
2. Give reasons:
a)Balloons filled with hydrogen rise to the ceiling.
b)Tractors have wide tyres.
c)A mug full of water appears light as long as it is under water in the bucket than when it is outside water.
3. State with reason whether work done is positive or negative in the following conditions : 

a) Work done by a man in lifting a bucket out of well by means of a pulley.

b) Work done by losing team in a tug of war.

c) Work done by an applied force on a body moving over a rough horizontal plane with uniform velocity.

d) Work done by a man in lifting a bucket out of well by means of a rope tied to a bucket

e) Work done by gravitational force in above case (d).

f) Work done by gravity on a freely falling object.

4. What kind of energy transformations taking place in the following :

(i)Burning of fuels (ii)Photosynthesis (iii)Arrow released from stretched bows.

5. Define: (i) amplitude (ii) frequency (iii) wave length.

6. What is meant by kinetic energy? Derive an expression for kinetic energy?

7. 50 waves pass through a point in 0.1 second. If the distance between one crest and the adjacent through is 0.34m, calculate frequency, wave length and wave velocity.

8. Represent graphically (a) loud sound and soft sound. (b) high pitch and low pitch sound.  

9. How much will a body of weight 35N weigh in water if it displaces 1 litre of water ?(g = 9.8m/s2)

10. (i) Which wave property determines (a) loudness (b) amplitude? 

5 MARKS QUESTIONS. 

1. a)Define power of a body . State and define the S.I unit of power.

b)Two children A and B both weighing 32kg start climbing up a rope separately and reach a height of 4m. A takes 10s and B takes 15s to reach that level. Calculate the amount of work done by A and B. Which of the two has more power? Show by calculation.

3. a) A body is floating on the surface of a liquid. With the help of a diagram

show the two forces acting on it that are responsible for its floatation.

State the relationship between these two forces in this case?

b)What is relative density? If an object is immersed wholly in a liquid causing up thrust equal to the weight of the body then what will be the relation between the relative densities of liquid and the object?

4. a)State the relation between commercial unit of energy and S.I unit of energy.

b)A man drops a 10kg rock from the top of 5m ladder. What is its K.E when it just touches the ground? What is its potential energy when it is at the top of ladder?

5. a)What is meant by ultrasound?

b)Explain the principle and working of SONAR?

6. State the law of conservation of energy. Illustrate the law by giving the example of a freely falling object.

10th SA – II Worksheet Physics CBSE Board

3 Mark Questions:-

1. What is the quantitative meaning attached to the term’ power of accommodation’ ? Why can’t we see clearly objects that are too close to the eye ? When do you have the least strain on the muscles of a normal eye ?
2. What is (i) cataract (ii) near point (iii) presbyopia.
3. What is the role of (i) ciliary muscle (2) iris (3) pupil (4) eye lens (5) light sensitive cells (6) retina
4. The near point of a hypermetropic person is 75 cm from the eye. What is the power of the lens required to enable him to read clearly a book held at 25 cm from the eye.
5. (i) A student allows a stream of white light passed through a medium of tiny particles. Which colour will get scattered the most ?
(ii) The refractive indices of diamond and rock salt are 2.42 and 1.54 respectively. If the speed of light in diamond is 1.2 X 108 ms-1, find the speed of light in rock salt.
6. (i) Four students observed an image and concluded that it is virtual, enlarged and erect. What is the nature of the reflecting/refracting surface ?
(ii) A convex mirror used on bus has a focal length of 200 cm. If a scooter is located at 100 cm from this mirror, find the position, nature and magnification of the image formed in the mirror.
7. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the total length of the lens.
8. (i) Define refractive index of a medium.
(ii) Draw diagrams to show the path of ray of light when it goes from (a) air to glass (b) water to air.
9. A person is unable to see the objects beyond 2 cm, clearly cause due to which this detect may arise. Draw ray diagrams to show (i) this defect of vision (ii) correction of this detect using appropriate lens.
10. Draw diagrams to show the refraction of yellow coloured light through a (i) rectangular glass slab (ii) a triangular glass prism.
5 Mark Questions:-
 Give reasons for the following.
1. Stars appear to twinkle
2. Sun appear reddish early in the morning
3. Sky appear dark instead of blue to an astronaut
4. Blue colour of sky
5. Danger signal lights are red in colour.
(i) Name the type of mirror used in the following situations (a) Head light of a car (b) rear-view mirror of a vehicle (c) to see a full length image of a tall building. (d) one half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object ? Verify your answer experimentally. Explain your observations.
(i) magnification produced by a lens is – 2. What does this mean.
(ii) (a) Two lenses have power of (i) + 2D (ii) – 4D, what is the nature and total length of each lens ?
(a) An object is kept at a distance of 100 cm from each of above lenses. Calculate the (i) image distance (ii) magnification in each of the two cases.
4. What is meant by dispersion of white light ? Describe the formation of rainbow in the sky with the help of a diagram. In dispersion of white light through prism, which colour deviates most and which colour the least? Why do they deviate differently ?

5. (a) With the help of a ray diagram, show the type of images formed when object is placed at the following positions in front of concave mirror.
(a) Between F and C (b) at F
(b) The radius of curvature of convex mirror, used on a moving automobile is 2.0 m. A truck is coming behind it at a constant distance of 3.5 m. Calculate (i) the position and (ii) the size of image relative to the size of the truck. What will be the nature of the image ?
6. (i) Draw a ray diagram to show passage of a ray of light through a rectangular glass slab, when the angle of incidence is zero.
(ii) what you mean by lateral displacement, Write any two factors on which it depends.
(c )with the help of an activity demonstrate the scattering white light.
7. (a) It is required to get (i) a magnified, erect and virtual image (ii) a diminished, erect and virtual image of a given object. What type of lens should we use in each case and where should the object be kept ?
(b) Draw ray diagrams to show the required image formation in each case.
(c) Which of these lenses could also form a magnified, real and inverted image ? Also indicate the position of the object for which this could happen ?
8. Draw a ray diagram in each case to show the position and nature of the image formed when the object is placed.
(i) at the centre of curvature of a concave mirror.
(ii) between the pole and focus of a concave mirror.
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a convex lens.
9. A convex lens is being used to get a three-fold magnified image of an object. The lens has a power of + 4.0D. Find the two positions of the object for this magnification and show the image formation in each case through the appropriate ray diagram.

10. A concave mirror produces three times magnified (enlarged) real image of an object 10 cm infront of it. Where is the image located ?

X (10) CBSE Sure Shoot Guess Question paper 2013-2014 (LIGHT – REFLECTION AND REFRACTION)

       Practice Set Paper - 01    

Q1 Name the type of mirror used in: Support your answer with reason. (a) Solar furnaces (b) Rear view mirror of a vehicle (c) Headlights of a car.

Q2 Draw the ray diagram to show (i) the position (ii) nature of the image formed when an object is placed between focus F and pole P of a concave mirror.

Q3 A concave mirror and a convex lens are held separately in water. What changes (if any) do you expect in the focal length of either?

Q4 A convex mirror used on an automobile has a focal length of 3m. If a vehicle behind is at a distance of 5 m ,  find the location of the image.

Q5 (i) Distinguish between a real and virtual image.  (ii)Distinguish between a convex and concave mirror.

Q6 We have to form an erect image of an object placed in front of a concave mirror of  focal length 15 cm. Draw the ray diagram.

Q7 Why does a ray falling normally on a plane mirror, retrace its path?

Q8 How do we locate the position of an image in a plane mirror? Show with an example.

Q9 Whatever may be the position of object, the image appears to be erect. Give the nature of mirror with reason.

Q10. From which surface of a mirror, the polished surface or the silvered surface, does most of the light reflect?

Q11. Draw a diagram showing the pole, focus, centre of curvature and principal’s axis of a concave mirror.

Q12. An object is placed at a distance of 12cmfrom a concave mirror of radius of curvature16cm. Find the position of the image.

Q13 What is the radius of plane mirror?

Q14 Why do we use convex surface for side view mirror?

Q15 Relate the focal length ‘f ‘ and the radius of curvature ‘R’.

Q16 Which kind of mirror is used in the headlights of a motor car and why?

Q17 What is focal length of a plane mirror?

Q18 A concave mirror is placed in water. Will there be any change in the focal length? Give reasons.

Q19 Name the type of mirror which always forms a virtual and diminished image.

Q20 Explain why a ray of light passing through the centre of curvature of a concave mirror gets reflected along the same path?

Practice Set Paper - 02

X Optics Numerical Problems from CBSE Board Paper

Q1. An object is placed at a distance of 30 cm from a concave mirror of focal length 20 cm. Where will the image be formed?

Q2. A 2.0-cm-high object is placed perpendicular to the principal axis of a concave mirror. The distance of the object from the mirror is 30 cm, and its image is formed 60 cm from the mirror, on the same side of the mirror as the object. Find the height of the image formed.

Q3. A 1.2-cm-long pin is placed perpendicular to the principal axis of a convex mirror of focal length 12 cm, at a distance of 8 cm from it. (a)Find the location of the image. (b)Find the height of the image. (c)Is the image erect or inverted?

Q4. Sunlight is incident on a concave mirror, parallel to its principal axis. The image is formed at a distance of 12cm from the pole. Find the radius of curvature of the mirror.

Q5.An object is placed at a distance of 20cm from a convex mirror of focal length 25cm.Calculate the position of the image. Discuss its nature.

Q5. A 2.0-cm-high object is placed at a distance of 20cm from a concave mirror. A real image is formed at 40cm from the mirror. Calculate the focal length of the mirror and size of the image.

Q6. Find the position, size and the nature of the image formed by a spherical mirror from the following data. u = -20cm f= -15cm ho= 1.ocm .

Q7. A 2-cm-high object is placed at a distance of 32cm from a concave mirror. The image is real, inverted and 3cm in size. Find the focal length of the mirror and the position of the image.

Q8. A concave mirror forms an inverted image of an object placed at a distance of 12cm from it. If the image is twice as large as the object, where is it formed?

Q9. A concave mirror forms an erect image of an object placed at a distance of 10cm from it. The size of the image is double that of the object. Where is the image formed?

Q10. An object is placed at a distance of 12cm from a concave mirror of radius of curvature 6cm.Find the position of the image.

Q11. An object of height 2cm is placed at a distance of 15 cm from a concave mirror of focal length 10 cm.Draw a scale diagram to locate the image. From the diagram, find the length of the image formed.

Q12. The image of an object placed 16 cm from a concave mirror is formed at a distance of 24 cm from the mirror. Calculate the possible focal lengths of the concave mirror from this information.

Q13. An object is placed 20 cm from a convex mirror. Its image is formed 12 cm from the mirror. Find the focal length of the mirror.

Q14.An object is placed at a distance of 12cm from a concave mirror. The image formed is real and four times larger than the object. Calculate the distance of the image from the mirror.

Q15. An object is placed 24cm from a concave mirror. Its image is inverted and doubles the size of the object. Find the focal length of the mirror and the position where the image is formed.

Q16. Where an object should be placed before a concave mirror of focal length 20cm so that a real image is formed at a distance of 60cm from it?

Q17. An object is placed at a distance of 12cm from a convex mirror of radius of curvature 12cm.Find the position of the image.

Q18. If the height of the object in the previous problem is 1.2cm, what will be the height of the image?

Q19. When a concave mirror is placed facing the sun, the sun's rays converge to a point 10cm from the mirror. Now, an erect, 2-cm-long pin is placed 15cm away on the principal axis of the mirror. If you want to get the image of the pin on a card, where would you place the card? What would be the nature and height of the image?

Q-20 the far point of a person suffering from myopia is 2 meters from the eye. Find the focal length and power of the corrective lens that will correct his vision.

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LESSON-5 (Changes Around Us)
Q1. Define fast change, irreversible change?
Q2 .Give different methods of preventing the rusting of iron.
Q3.Why curd cannot be converted back into milk?
Q4 Why sugar becomes brownish black and taste bitter when heated ?
Q5. Why breaking of chalk is a physical change ?
Q6. Give examples for the following types of changes “

1. Fast, chemical and irreversible change.
2. Fast, physical, irreversible change.
3. Formation of biogas from cowdung.

Q7. What type of change is burning of wood and why ?
Q8.State whether energy is absorbed or evolved in each of the following changes :
(a) Preparation of food by plants (b) Lightening (c) Volcanic eruptions (d) Vaporizations of alcohol 

 (e) Formation of curd from milk (f) Burning of fuels
Q9. What is meant by pasteurization ? What is the advantage of pasteurization milk?
Q10. Classify the following changes into more than one way :
(a) Melting of glass (b) Tearing of cloth (c) Formation of fruit from flower (d) Spoiling of milk
(e) Moulding of clay (f) Rusting of iron (g) Bursting of crackers
LESSON-8 (Structure and Function of living organisms- Plants)
Q1. What will happen if green plants do not get sunlight ?
Q2. Define the following : (a) Node (b) Internode (c) Pollen grains (d) Ovules
3. In which category of plant potato falls and why?
Q4. Why do some plants trap insects?
Q5. What is bark in plants? What is its functions?
Q6. How does root system prevent soil erosion?
Q7. What is the stem of cactus plant thick and green?
Q8. What is leaf venation? What are its different types?
Q9. What does a seed contains?
Q10. Give the functions of a leaf?
Q11. Why are certain parts of the plants modified?
Q12. What are ornamental plants?
LESSON-9 (Structure and Function of living organisms- Animals)
Q1. A substance `x’ flows from heart into arteries and then into capillaries. It is brought back to the heart by veins. Name the substance `x’.
Q2. What is the special name of the fertilized egg?
Q3. What is the role of hair and mucus on the inner lining of nose in breathing?
Q4. Name the reproductive organs of male and female human. What do these organs produce?
Q5. Who does our tongue helps in digestion?
Q6. Name the various blood groups in human body?
Q7. Which pigment give red colour to blood?
Q8. Name the two main glands associated with alimentary canal.
Q9. Differentiate between arteries and veins?
Q10. Give the main function of the spinal cord.
Q11. Why it is not advisable to breath through mouth?
Q12. Name the various sense organs present in our body and write there functions
LESSON-13 (Magnets)
Q1. Where is magnetite found ?
Q2 .Why is magnetite known as ‘loadstone’ ?
Q3.Differentiate between natural and man-made magnets ?
Q4.(a) What are electromagnets ? How does it work ? (b) Where are they used ?
Q5. How is the strength of a magnet determined ?
Q6. ‘Our planet earth behaves like a magnet.’ Explain.
Q7. How do you understand by ‘magnetic keepars’ ?
Q8.Why should we not place magnets near a computer or a cell phone ?
Q9. How does a magnet loose its power ?
Q10. Write an activity to show that the magnet is maximum near the poles.
LESSON-14 (Fabric from fibres)
Q1. What do you mean by fabric ?
Q2 .What type of clothes should we wear ?
Q3.Why is fresh soil required every year for growing jute plants ?
Q4. How did the word ‘NYLON’ got its name ?
Q5. Which fibre is called as golden fibre and why ?
Q6. Define the following terms – (a) Fleece (b) Weaving (c) Spinning (d) Cotton bolls
Q7.Which type of soil is required for the growth of coconut trees and why ?
Q8.What is a weaver ?
Q9. Which material is used for making raincoat and why ?
Q10.Why is black soil good for growing cotton ?
LESSON-10 (Work and Energy)
Q1. What is the Principal of Conservation of Energy ?Q2 .Write two uses of solar cells.
Q3.Define (a) Potential Energy (b) Kinetic Energy
Q4. Boil some water in a container covered with a lid. What do you observe ? Give reason.
Q5. How is heat energy useful to us ?
Q6. How is sound produced ?
Q7. What is mechanical energy ?
Q8.What happens when we strike a match stick against a match box ? Give reason also.
Q9. What do you mean by chemical energy ?
Q10. What kind of energy conversion of energy takes place in the following :
Radio (2) Electric bell (3) Electric bulb (4) Torch cell (5) Sitar (6) Geyser (7) Electric train (8) Hydroelectric Dam (9) Cars (10) Wind mill
LESSON-11 (Electric Current and Circuits)
Q1. Write any two advantages of dry cell.
Q2 .Differentiate between primary and secondary cells.
Q3.What are button cells ?
Q4. Why are CFLs recommended by environmentalist ?
Q5. How can we show that air is an insulator ?
Q6. Suggest any four ways by which we can minimize the use of electricity.
Q7. “Electricity is a good servant but a bad master”. Comment.
Q8.Why are inside of electric bulbs filled with inert gases ?
Q9. Why is concave mirror used inside a torch ?
Q10. What does LED stand for ? Why are they preferred over electric bulbs ?
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Class 9 and 10 CBSE Maths and science Solved Papers for SA-2

CLASS IX SUMMATIVE ASSESSMENT II SAMPLE PAPERS FOR SCIENCE
1.Science_IX_Summative Assessment Term-II- Sample Paper-I
2.Science IX Summative Assessment Term-II-Sample Paper-II
3.Science IX Summative Assessment Term-II-Sample Paper-III
4.Science IX Summative Assessment Term-II-Sample Paper- IV
5.Science IX Summative Assessment Term-II-Sample Paper -V
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CBSE-10-Science-Sample-Paper-for-Term-2

SUMMATIVE ASSESSMENT-II

SCIENCE

Time allowed: 3 hours                                                                                     Maximum Marks:80

SECTION-A

1. Which compounds are responsible for the depletion of ozone layer? 1
2. Define, 'trophic level'. 1
3. Give an example of optical phenomena which occur in nature due to atmospheric refraction. 1
4. Write the electron dot structure of ethene molecule, C ₂ H₄    1
5. Explain why the planets do not twinkle but the stars twinkle. 2
6. Write any two differences between binary fission and multiple fission in a tabular form as observed in cells of organisms. 2
7. List any four modes of asexual reproductions. 2
8. List any four characteristics of a good fuel. 2
9. What are non-renewable resources of energy?  Give two examples of such resources. 2
10. Answer:

1.      How do you calculate the possible valency of an element from the electronic configuration of its atoms?

2.      Calculate the valency of an element X whose atomic number is 9.  2

11. The atomic numbers of three elements, X, Y and Z are 9, 11 and 17 respectively.  Which two of these elements will show similar chemical properties?  Why?  2
12. State the two laws of reflection of light.  2
13. Draw a ray diagram to show the refraction of light through a triangular glass prism and mark angle of deviation on it.  2
14. What eye defect is hypermetropia?  Describe with a ra diagram how this defect of vision can be corrected by suign an appropriate lens. 3
15. Answer:

1.      List two sexually transmitted diseases in each of the following cases: 3

1.      Bacterial infections

2.      Viral infections

2.      How may the spread of such diseases be prevented?

16. Explain Mendel's view of a dominant trail.  Give an example. 3
17. Explain the terms: 3

1.      Speciation

2.      Natural selection

18. Explain how equal genetic contribution of male and female parents is ensured in the progency.3
19. What is an 'esterification' reaction?  Describe an activity to show esterification. 3
20. Two elements X and Y belong to group 1 and 2 respectively in the same period of periodic table.  Compare them with respect to: 3

1.      the number of valence electrons in their atoms

2.      their valencies

3.      metallic character

4.      the sizes of their atoms

5.      the formulae of their oxides

6.      the formulae of their chlorides

21. Draw the ray diagram and also state the position, the relative size and the nature of image formed by a concave mirror when the object is placed at the centre of curvature of the mirror. 3
22. A ray of light travelling in air enters obliquely into water.  Does the light ray bend towards or away from the normal?  Why?  Draw a ray diagram to show the refraction of light in this situation. 3
23. Answer:

1.      Draw a diagram of the longitudinal section of a flower and label on it sepal, petal, ovary and stigma.

2.      Write the names of male and female reproductive parts of a flower.                               5

                                                                     OR

3.      What is fragmentation in organisms?  Name a multicellular organism which reproduces by this method.

4.      What is regeneration in organism?  Describe regeneration in Planaria with the help of a suitable diagram.

24. Answer:

1.      In a tabular form, differentiate between ethanol and ethanoic acid under the following heads: 5

1.      Physical state

2.      Taste

3.      NaHCO₃ test

4.      Ester test

2.      Write a chemical reaction to show the dehydration of ethanol.

OR

3.      What is a soap?  Why are soaps not suitable for washing clothes when the water is hard?

4.      Explain the action of soap in removing an oily spot from a piece of cloth.

25. Anaswer:                     5

1.      If the image formed by a lens is diminished in size and erect, for all positions of the object, what type of lens is it?

2.      Name the point on the lens through which a ray of light passes undeviated.

3.      An object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm.  The distance of the object from the lens is 30 cm.  Find (I) the position (ii) the magnification and (iii) the nature of the image formed.

OR

4.      One half of a convex lens is covered with a black paper.  Will such a lens produce an image of the complete object?  Support your answer with a ray diagram.

5.      An object 5 cm high is held 25 cm away from a converging lens of focal length 10 cm.

1.      Draw the ray diagram and

2.      Calculate the position and size of the image formed.

3.      What is the nature of the image.