*Level – I (Single Choice Questions)*

1. A meter washer has a hole of diameter d_{1} and an external diameter d_{2} , where 3d_{2} = d_{1}. On heating, d_{2} increases by 0.3%. Then d_{1} will

(a) decrease by 0.1%

(b) decrease by 0.3%

(c) increase by 0.1%

(d) increase by 0.3%

2.If *I* is the moment of inertia of a solid body, the change in *l *corresponding to a small change in temperature is

(a) αIΔT

(b) (1/2)αIΔT

(c) 2αIΔT

(d) 3αIΔT

3.If α is the coefficient of linear expansion, the change in the period *t* of a physical pendulum with temperature change of ΔT is

(a) (1/2) αtΔT

(b) (1/4) αtΔT

(c) (3/4) αtΔT

(d) (1/3) αtΔT

4. A steel scale is to be prepared such that the millimeter intervals are to be accurate within 6 x 10^{-5} mm . The maximum temperature variation during the ruling of the millimeter marks (α =12 x 10^{-6} C^{-1}) is

(a) 4.0ºC

(b) 4.5ºC

(c) 5.0ºC

(d) 5.5ºC

5. A block of ice at –10ºC is slowly heated and converted to steam at 100ºC. Which of the following curves represents the phenomenon qualitatively ?

(a)

(b)

(c)

(d)

6. A point source of heat of power P is placed at the center of a spherical shell of mean radius R. The material of the shell has thermal conductivity k. If the temperature difference between the outer and the inner surface of the shell is not to exceed T, then the thickness of the shell should not be less than

(a)

(b)

(c)

(d)

7. Three rods *A, B *and *C* have the same dimensions. Their thermal conductivities are and respectively. *A* and *B* are placed end to end, with their free ends kept at a certain temperature difference. C is placed separately, with its ends kept at the same temperature difference. The two arrangements conduct heat at the same rate. must be equal to

(a)

(b)

(c)

(d)

8. A cyclic process is shown in the *p*–*T* diagram. Which of the curves show the same process on a *V-T* diagram ?

(a)

(b)

(c)

(d)

9. A solid at temperature *T*_{1} is kept in an evacuated chamber at temperature . The rate of increase of temperatrue of the body is proportional to

(a) T_{2} – T_{1}

(b) T_{2}^{2} – T_{1}^{2}

(c) T_{2}^{4} – T_{1}^{4}

(d) T_{2}^{3} – T_{1}^{3}

10. 70 calories of heat are required to raise the temperature of 2 moles of an ideal gas at constant pressure from 30ºC to 35ºC. The amount of heat required in calories to raise the temperature of same gas through the same range (30ºC to 35ºC) at constant volume is

(a) 30

(b) 50

(c) 70

(d) 90.

1.(d) 2.(c)

3.(a) 4.(c)

5.(a) 6.(b)

7.(b) 8.(c)

9.(c) 10.(b)