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#### Term 1 Four Mark Model Questions

10th Standard EM

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Science

Time : 02:00:00 Hrs
Total Marks : 60
15 x 4 = 60
1. Two bodies have a mass ratio of 3:4 The force applied on the bigger mass produces an acceleration of 12 ms-2.What could be the acceleration of the other body, if the same force acts on it.

2. Calculate the coefficient of cubical expansion of a zinc bar. Whose volume is increased 0.25 m3 from 0.3 m3 due to the change in its temperature of 50 K.

3. State Ohm’s law.

4. Distinguish between the resistivity and conductivity of a conductor.

5. A piece of wire having a resistance R is cut into five equal parts.
a) How will the resistance of each part of the wire change compared with the original resistance?
b) If the five parts of the wire are placed in parallel, how will the resistance of the combination change?
c) What will be ratio of the effective resistance in series connection to that of the parallel connection?

6. Mention two cases in which there is no Doppler effect in sound?

7. Two observers are stationed in two boats 4.5 km apart. A sound signal sent by one, under water, reaches the other after 3 seconds. What is the speed of sound in the water?

8. Define critical mass.

9. What is stellar energy?

10. N2 + 3 H2 → 2 NH3
(The atomic mass of nitrogen is 14, and that of hydrogen is 1)
1 mole of nitrogen (_______g) +
3 moles of hydrogen ( _________ g) →
2 moles of ammonia ( _________ g)

11. Give the salient features of “Modern atomic theory”

12. The electronic configuration of metal A is 2,8,18,1.
The metal A when exposed to air and moisture forms B a green layered compound. A with con. H2SO4 forms C and D along with water. D is a gaseous compound. Find A,B,C and D.

13. In what way hygroscopic substances differ from deliquescent substances

14. What are called thermolysis reactions?

15. What is a chemical equilibrium? What are its characteristics?