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from DAV PUBLIC SCHOOL, asked a question
Subject: Science , asked on 20/9/12
1 draw the diagram

1. At what temperature does solid ice and liquid water co-exist together ? (1)

2. An athlete always runs some distance before taking a jump. Why ? (1)

3. Name the cell organelle, other than mitochondria, that has its own DNA and
Ribosomes. (1)

4. How can you obtain pure copper sulphate from an impure sample ? (2)

5. Gravitational force acts on all objects in proportion to their masses. Why does then
a heavy object not fall faster than a light object ? (2)

6. What is endocytosis ? Name an organism that feeds by this method. (2)

7. (a) In the diagram of location of meristematic tissue in plant body given below,
identify the type of meristematic tissue found in the regions marked ‘A’ and
‘B’ of a stem.3
(b) State one function of each region. (2)
draw the diagram

8. A gas jar containing air is placed upside down on a gas jar of bromine vapour. It
is observed that after some time, the gas jar containing air also becomes completely
reddish brown.
(a) Explain why this happens.
(b) Name the process involved. (3)

B
A
B4
9. Observe the apparatus shown below and answer the following questions :
(a) Name the apparatus.
(b) State one use of the apparatus.
(c) State the principle involved in this process. (3)

10. A bus accelerates uniformly from 54 km/h to 72 km/h in 10 s. Calculate :
(i) the acceleration in ms
–2
.
(ii) the distance covered by the bus in meters during this interval. (3)

11. A truck starts from rest and rolls down a hill with a constant acceleration. It
travels a distance of 400 m in 20 seconds. Find the acceleration. Find the force
acting on it if its mass is 7 metric tonne. [1 metric tonne = 1000 kg]. (3)
,
12. (a) Distinguish between universal gravitational constant and acceleration due to
gravity.
(b) Two objects, of masses m1
and m2
, when separated by a distance ‘d’ in air,
attract each other with a force of 4N. How is the magnitude of the force
changed when the masses of both objects are reduced to one half without
changing the distance between them. (3)

13. According to the third law of motion, when we push on an object, the object pushes
back on us with an equal and opposite force. If the object is a massive truck parked
along the road side, it will probably not move even if we apply a force on it. A
student justifies this by answering that the two opposite and equal forces cancel
each other. Comment on this logic and explain why the truck does not move. (3)

14. An object, kept near the edge, falls from a hill and hits the ground in 0.5 s
(g ~ 10 m/s
).
(i) What is the speed of the object when it hits the ground ?
(ii) What is its average speed during its fall ?
(iii) How high is the hill from the ground ? (3)

15.
(a) Identify the tissue.
(b) Infer the characteristic features of these cells.
(c) Specify the function of the tissue.
(d) Name any one part of the plant where these cells are present. (3)

16. List any three differences between epithelial tissue and connective tissue
(b) Why are organisms like bacteria called prokaryotes ? (3)

18. (a) What suggestions can you give to an agriculturist to combine fish culture in
his crop field ?
(b) What is mariculture ? (3)
(a) ,d oQ"kd dks mldh oQf"k ;ksX; Hkwfe esa vki fdl iQly osQ lkFk eNyh lao/Zu d
19. What precautions should be taken for the application of fertilizers in the cultivated
field ? List any two disadvantages of excessive use of fertilizers. (3)

20. (a) Define solution. If 10 mL of H2 draw diagram
SO4
is dissolved in 90 mL H2O, calculate the
concentration of H2
SO4
in the solution.
(b) Give any two characteristics of compounds.
(c) What do we get when two or more elements are (chemically) combined? (5)

(a) 110 g of salt is present in 550 g of solution. Calculate the concentration of the
solution.
(b) List in tabular form any three differences between true solution, colloidal
solution and suspension.

21. Distinguish, in tabular form, between solids, liquids and gases under the following
characteristics :
(i) intermolecular attraction;
(ii) density;
(iii) fluidity;
(iv) diffusion;
(v) kinetic energy of particles at a given temperature. (5)
OR
What is evaporation ? In the following examples state which factor is responsible
for the change in rate of evaporation and how :
(i) Clothes dry faster on a windy day;
(ii) Wet clothes dry faster on spreading them;
(iii) Clothes dry faster in sun than in shade;
(iv) Clothes take longer time to dry on a rainy day.

22. (a) Explain why is it difficult to walk on sand.
(b) Why is the recoil of a heavy gun, on firing, not so strong as that of a light gun
using the same cartridges ?
(c) A constant force acts on an object of 5 kg for a period of 2 s. It increases the
velocity of the object from 3 m/s to 7 m/s. Find the magnitude of the applied
force. Now, if the force was applied for a period of 5 s, what would be the final
velocity of the object ? (5)

State the law of conservation of momentum. Show how it can be verified using
Newton’s third law of motion.
laosx laj{k.k dk fu;e D;k gS U;wVu osQ xfr osQ rhljs fu;e dk mi;ksx djosQ bl fu;e dk
lR;kiu dhft,A23. The following table gives the data about the motion of a car :
Time (h) 11.00 11.30 12.00 12.30 1.00
Distance (km) 0 30 30 65 100
Plot the distance-time graph.
From the graph
(i) Find the average speed of the car between 12.00 hours and 12.30 hours.
(ii) What is the average speed of the car ?
(iii) Is the car’s motion an example of uniform motion ? Justify. (5)

An object is moving along a straight line with uniform acceleration. The following
table gives the velocity of the object at various instants of time.
Time (s) 0 1 2 3 4 5 6
Velocity (m/s) 2 4 6 8 10 12 14
Plot the velocity-time graph.
From the graph
(i) Find the velocity of the object at the end of 2.5 s.
(ii) Calculate the acceleration of the object.
(iii) Calculate the distance covered in the last 4 s.

24. (a) Give the two types of food requirements of dairy animals.
(b) Mention the two forms of the animal feed.
(c) State the role of micronutrient feed additives that are added in the food of
dairy animals. (5)
,
(a) What is intercropping ?
(b) How does intercropping give better returns to the farmers than the normal
method of cultivation ?
(c) State any four losses due to the biotic and abiotic factors during storage of
grains.

25. In which of the following, sediment will not be observed on standing for some
time ? (1)
(a) Chalk powder and water (b) Egg albumin and water
(c) Soil and water (d) Fine sand and water

1026. A mixture of soil and water was shaken well and then tested for its apperance,
stability and sedimentation. The correctly reported set of observation is : (1)
Appearance Stability Sedimentation
(a) Opaque Unstable Sediment
(b) Opaque Stable Sediment
(c) Transparent Unstable No Sediment
(d) Transparent Stable No Sediment
27. In which of the following mixtures the separation of the components may be done
using a magnet ? (1)
(a) a mixture of ferrous sulphide and copper sulphide
(b) a mixture of iron filings and ferrous sulphide
(c) a mixture of sulphur powder and ferrous sulphide
(d) a mixture of carbon-di-sulphide and ferrous sulphide
28. Four students performed the following experiments and recorded their observations.
The correct recording is that of student ? (1)
Student Procedure Observation
(a) Mixed powder of Barium The mixture turned yellow.
Chloride and Sodium Sulphate.
(b) Mixed solutions of Barium Thick white precipitate was formed.
Chloride and Sodium Sulphate.
(c) Added Sodium Sulphate powder Solution turned yellow.
to Barium Chloride solution.
(d) Added Barium Chloride powder No change was observed.
to Sodium Sulphate solution.

29. A student sets up an apparatus for the determination of boiling point of a sample
of water supplied to him in his laboratory. He recorded the boiling point as 102°C.
Assuming that the thermometer is accurate, the determined value of boiling point
is due to : (1)
(a) the water may be containing large amount of sand.
(b) the water may be containing some common salt.
(c) the bulb of the thermometer is not kept above the water surface.
(d) the bulb of the thermometer is touching the bottom of the vessel containing
water.
30. In the determination of melting point of ice, a student observed with the help of
thermometer, that : (1)
(a) whole of ice melts and temperature starts decreasing.
(b) ice starts melting and temperature becomes constant.
(c) ice starts melting and temperature starts rising.
(d) temperature starts rising but ice does not melt.

31. While separating the components of a mixture of sand, camphor and common salt
Mohan added water to the mixture in a beaker and stirred it well. He observed
that component that has dissolved in water is : (1)
(a) camphor (b) both camphor and common salt
(c) sand (d) common salt.

32. Which one of the following will result into the formation of compound of iron and
sulphur? (1)
(a) Mixing of iron filings and sulphur powder at room temperature.
(b) Adding iron filings to molten sulphur.
(c) Heating the mixture of iron filings and sulphur powder.
(d) Addition of carbon disulphide to a mixture of iron filings and sulphur powder.

33. When a strip of Magnesium is burnt in air : (1)
(a) dazzling white flame is seen. (b) red flame is seen.
(c) blue flame is seen. (d) green flame is seen.

1334. The correct sequence of steps for separating a mixture of sand, ammonium chloride
and sodium chloride is : (1)
(a) Sublimation, evaporation, adding water, filtration.
(b) Sublimation, adding water, filtration, evaporation.
(c) Evaporation, sublimation, adding water, filtration.
(d)
35. A student is asked to identify the process which occurs when the raisins are soaked
in water. The process is :
36. Two spring balances A and B are connected draw the diagram
as shown. Balance B has a zero error and
shows a reading of 2 gf when unstretched.
There is no zero error in balance A.
Balance A is now stretched by applying a force on it. If balance B shows a reading
of 50 gf, the reading of balance A would be : (1)

(a) 52 gf (b) 50 gf
(c) 49 gf (d) 48 gf
1437. Students were instructed to add a few drops of iodine solution to each of the following
samples.
cooked idly rice powder talcum power glucose
The content would turn blue black in : (1)
(a) A and B (b) B and C
(c) C and D (d) D and A.

38. Dal adulterated with metanil yellow was boiled in water. HCl was added. The
colour of content will turn :
(a) red (b) pink
(c) orange (d) violet. (1)
with practical

(c) l arjh (d) tkequhA
39. On observing an onion peel slide under low power of a compound microscope,
the set of structures clearly seen is :
(a) cell wall, cell membrane, nucleus, cytoplasm
(b) nucleus, cell membrane, vacuole, chromosomes
(c) cell wall, cell membrane, mitochondria, vacuole
(d

40. The observed feature which is not
the percentage of water absorbed was :
(a) same in beaker A and B (b) more in A than in B
(c) more in B than in A (d) twice as much in B as in A. (1)

42. Two springs balances A and B are connected as shown. Balance A has a least
count of 2 gf while balance B has a least count of 5 gf. There is no zero error in
either of the two balances.
When a force is applied to stretch balance
A, its pointer moves through 30 divisions
on its scale. The number of divisions,
through which the pointer of balance B
would move, would be :

When we walk on hard ground, the force with which our foot pushes the ground is equal to the force with which the ground pushes the foot. Since, the ground is hard it doesn’t change its shape and we walk easily. While in sand, a part of the force by our foot is used up in displacing the sand. So, the reaction force now is smaller. So, it becomes difficult to walk on sand.

__

Suppose:

Mass of bullet = m

Mass of gun = M

Velocity of bullet = v

Recoil velocity of the gun = V

Initially the gun and bullet were at rest, so, the initial momentum of the system is, P i = 0

After firing the momentum of the system = momentum of gun + momentum of bullet

=> P f = MV + mv

By conservation of momentum,

P f = P

=> MV + mv = 0

=> V = -(mv)/M

The negative sign indicates that the direction of velocity of gun is opposite to that of the bullet.

For a lighter gun, M is smaller, so V will be large. And for a heavy gun M is larger and V will be smaller.

So, recoil velocity of a heavier gun is comparatively smaller.

___

We have,

Initial velocity,  u =3 m/s

Final velocity, v = 7 m/s

Mass of the body, m = 5 kg

Now, acceleration, a = (v - u)/t = (7 - 3)/2 = 2 m/s 2

So applied force, F = ma = (5)(2) = 10 N

If the force was applied for 5 s the final velocity would be,

v = u + at

=> v = 3 + (2)(5) = 13 m/s

___

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38. colour will turn pink.

39. cell wall, cell membrane, mitochondria, nucleus

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