Physics Times 07.2019

(c)

2 2 2 2 2 2

1 1 2 2 3 3

1 1 2 2 3 3

n T n T n T

n T n T n T

 

 

(d)

 

[2009]

[2008]

[2007]

CALORIMETRY
[ONLINE QUESTIONS]

[2017]

[2015]

3.

[2014]

4.

[2013]

5.

[2013]

[OFFLINE QUESTIONS]

1.

[2017]

1 2 3

3

T T T

7. One kg of a diatomic gas is at a pressure of

8 10^4 N m/.^2 The density of gas is 4 / .kg m^3

What is the energy of the gas due to its

thermal motion? [2009]

(a) 5 10^4 J (b) 6 10^4 J

(c) 7 10^4 J (d) 3 10^4 J

8. The speed of sound in oxygen ( )O 2 at certain

temperature is 460 ms^1. The speed of sound

in helium (He) at the same tempreature will

be (assume both gases to be ideal) [2008]

(a) 1421 ms^1 (b) 500 ms^1

(c) 650 ms^1 (d) 330 ms^1

9. If CP and CV denote the specific heats of

nitrogen per unit mass at constant pressure

and constant volume respectively, then

[2007]

(a) CP CV 28 R (b) CP CV R/ 28

(c) CP CV R/ 14 (d) CP CV R

CALORIMETRY

[ONLINE QUESTIONS]

1. In an experiment a sphere of aluminium of
   mass 0.20 kg is heated upto 150 .C
   Immediately, it is put into water of volume
   150 cc at 25 C kept in a calorimeter of
   water equivalent to 0.025 kg. Final
   temperature of the system is 40 .C The
   specific heat of aluminium is: [2017]
   (a) 378 /J kgC (b) 315 /J kgC
   (c) 476 /J kgC (d) 499 /J kgC


2. An experiment takes 10 minutes to raise the
   temperature of water in a container from 0 C
   to 100 C and another 55 minutes to convert
   it totally into steam by a heater supplying
   heat at a uniform rate. Neglecting the
   specific heat of the container and taking

specific heat of water to be

1 cal gC, the heat of vapourisation

according to this experiment will come out

to be [2015]

(a) 560 cal/g (b) 550 cal/g

(c) 540 cal/g` (d) 530 cal/g

3. A kettle with 2 L water at 27 C is heated by
   operating coil heater of power 1kW. The heat
   is lost to the atmosphere at constant rate
   160 J, when it is open. In how much time will
   water be heated to 77 C(sp. heat of water
   = 4.2 kJ/kg) with lid open? [2014]
   (a) 14 min (b) 7 min
   (c) 8 min 20 s (d) 6 min 2 s


4. A mass of 50g of water in a closed vessel,
   with surroundings at a constant temperature
   takes 2 minutes to cool from 30 to 25 . C C AA
   mass of 100g of another liquid in an identical
   vessel with identical surroundings takes the
   same time to cool from 30 to 25 . C C The
   specific heat of the liquid is: (The water
   equivalent of the vessel is 30g.) [2013]
   (a) 2.0 kcal/kg (b) 7 kcal/kg
   (c) 3 kcal/g (d) 0.5 kcal/kg


5. 500 g of water and 100g of ice at 0 C are in
   a calorimeter whose water equivalent 40g.
   10g of steam at 100 C is added to it. then
   water in the calorimeter is: (Latent heat of
   ice = 80 cal g/ , Latent heat of steam
   = 540 cal g/ ) [2013]
   (a) 580 g (b) 590 g (c) 600 g (d) 610 g

[OFFLINE QUESTIONS]

1. A copper ball of mass 100 gm is at a
   temperature T. It is dropped in a copper
   calorimeter of mass 100 gm, filled with
   170 gm of water at room temperature.
   subsequently, the temperature of the system
   is found to be 75 .C T is given by (Given:
   room temperature  30 ,C specific heat of
   copper 0.1cal/ gmC) [2017]
   (a) 1250 C (b) 825 C
   (c) 800 C (d) 885 C