Questions OBJECTIVE - I and Answer (Calorimetry) HC Verma Part II

Q#1

The specific heat capacity of a body depends on

(a) the heat given

(b) the temperature raised

(c) the mass of the body

(d) the material of the body.

Answer: (d)   

Explanation: Specific heat capacity is a property of the material due to which same masses of different materials need different amounts of heat to get the same temperature difference. Hence the option (d). 

Q#2

Water equivalent of a body is measured in

(a) kg

(b) calorie

(c) kelvin

(d) m³ 

Answer:  (a)   

Explanation: The mass of water that has the same heat capacity that of the given body is called the water equivalent of that body. So this mass is measured in kg. Option (a).

Q#3

When a hot liquid is mixed with a cold liquid, the temperature of the mixture

(a) first decreases then become constant

(b) first increases then become constant

(c) continuously increases

(d) is undefined for some time and then becomes nearly constant

Answer:  (d)   

Explanation: When hot and cold liquids are mixed, the molecules of both liquids takes some time to spread evenly and to transfer their energies. During this time the temperature is undefined. After this process is complete the temperature is nearly constant. Option (d). 

 

Q#4

Which of the following pairs represent units of the same physical quantity? 

(a) kelvin and joule

(b) kelvin and calorie

(c) newton and calorie

(d) joule and calorie.  

Answer:  (d)   

Explanation: Joule and calorie both are units of energy. Traditionally heat was measured in calories. When it was established that heat is also a form of energy and mechanical work can also produce heat and raise the temperature, the relationship between calorie and joule was established through experiments. 1 Calorie = 4.186 Joule. Hence option (d). 

Q#5

Which of the following pairs of physical quantities may be represented in the same unit?

(a) heat and temperature

(b) temperature and mole

(c) heat and work

(d) specific heat and heat.  

Answer:  (c)   

Explanation: Heat is a form of energy, so both can be represented in the same unit. But energy is the capacity to do work and both are represented in the same unit. Hence heat and work can be represented in the same unit. The option (c). 

Q#6

Two bodies at different temperatures are mixed in a calorimeter. Which of the following quantities remains conserved?

(a) the sum of the temperatures of the two bodies 

(b) total heat of the two bodies

(c) total internal energy of the two bodies

(d) the internal energy of each body. 

Answer:  (c)   

Explanation: When two bodies at different temperatures are mixed in a calorimeter, energy flows from the body at a higher temperature to the body at a lower temperature. This energy in transit is called heat. Once both the bodies reach the same temperature and the energy transfer is complete it becomes the internal energy of the receiving body. Since in a calorimeter heat neither can enter nor can escape total internal energy of two bodies remain constant. Option (c).

Q#7

The mechanical equivalent of heat

(a) has the same dimension as heat

(b) has the same dimension as work

(c) has the same dimension as energy

(d) is dimensionless. 

Answer: (d)   

Explanation: If mechanical work W produces the same temperature Change as heat H, it is written

W = JH, where J is called the mechanical equivalent of heat.

So, J = W/H.

Since W and H have the same dimensions, J will be dimensionless. The option (d).