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Physics M.C.Q (1 Marks)

Calorimetry · Rajasthan Board (RBSE) STD 12 Science (Rajasthan - English Medium). 9 questions.

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M.C.Q (1 Marks)

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9 questions · auto-graded multiple-choice test.

MCQ 11 Mark
The ratio of specific heat capacity to molar heat capacity of a body:
  • A
    Is a universal constant.
  • B
    Depends on the mass of the body.
  • ✓
    Depends on the molecular weight of the body.
  • D
    Is dimensionless.
Answer
Correct option: C.
Depends on the molecular weight of the body.
Explanation:
Specific heat capacity of a body, $\text{s}=\frac{\text{Q}}{\text{m}\triangle\theta}$
Here,
Q = Heat supplied
m = Mass of body
$\triangle\theta$ = Change in temperature
Molar heat capacity of a body,
$\text{C}=\frac{\text{Q}}{\text{n}\triangle\theta}$
Here,
Q = Heat supplied
n = Number of moles
$\triangle\theta$ = Change in temperature
$\therefore$ The ratio of the specific heat capacity and molar heat capacity is given by,
$\frac{\text{s}}{\text{C}}=\frac{\frac{\text{Q}}{\text{m}\triangle\theta}}{\frac{\text{Q}}{\text{m}\triangle\theta}}=\frac{\text{n}}{\text{m}}=\frac{\text{n}}{\text{nM}}=\frac{1}{\text{M}}$
Here,
M = Molar mass related to number of moles
m = Mass
As the value of M is different for different bodies of different composition, the ratio cannot be a universal constant.
Also, the ratio is independent of the mass of the body.
The ratio of the specific heat and molar heat capacity depends on the molecular weight of the body.
Clearly, the unit of molecular weight is kg/mole. So, the ratio that depends only on the molecular weight cannot be dimensionless.
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MCQ 21 Mark
When a hot liquid is mixed with a cold liquid, the temperature of the mixture:
  • A
    First decreases then becomes constant.
  • B
    First increases then becomes constant.
  • C
    Continuously increases.
  • ✓
    Is undefined for some time and then becomes nearly constant.
Answer
Correct option: D.
Is undefined for some time and then becomes nearly constant.
Explanation:
When hot liquid is mixed with cold liquid, the molecules collide and transfer heat. When heat is transferred, the temperature is undefined. Once the heat energy is shared by the molecules, the system reaches equilibrium and the temperature becomes nearly constant.
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MCQ 31 Mark
Which of the following pairs represent units of the same physical quantity?
  • A
    Kelvin and joule.
  • B
    Kelvin and calorie.
  • C
    Newton and calorie.
  • ✓
    Joule and calorie.
Answer
Correct option: D.
Joule and calorie.
One calorie is defined as the amount of heat needed to raise the temperature of $1g$ of water from $14.5^{\circ}$ to $15.5^{\circ}$ at the pressure of $1\ \ce{atm}.$ Heat is a form of energy and the unit of energy is joule.
Therefore, joule and calorie represent energy.
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MCQ 41 Mark
Two bodies at different temperatures are mixed in a calorimeter. Which of the following quantities remains conserved?
  • A
    Sum of the temperatures of the two bodies.
  • B
    Total heat of the two bodies.
  • ✓
    Total internal energy of the two bodies.
  • D
    Internal energy of each body.
Answer
Correct option: C.
Total internal energy of the two bodies.
Explanation:
When two bodies at different temperatures are mixed in the calorimeter, heat flows from one body to the other due to the temperature difference. This results in change in the internal energy of the individual bodies. There is no exchange of heat with the surrounding in the calorimeter. Thus, the total internal energy of the bodies remain conserved as no external work is done on them.
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MCQ 51 Mark
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.
  • ✓
    Is dimensionless.
Answer
Correct option: D.
Is dimensionless.
Explanation:
If the mechanical work done (W) produces the same temperature change as heat (H), then the mechanical equivalent of heat (J) is equal to $\frac{\text{W}}{\text{H}}.$ Thus,
$\text{J}=\frac{\text{W}}{\text{H}}$
Since the unit of work and heat is the same, mechanical equivalent of heat is dimensionless.
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MCQ 61 Mark
Which of the following pairs of physical quantities may be represented in the same unit?
  • A
    Heat and temperature.
  • B
    Temperature and mole.
  • ✓
    Heat and work.
  • D
    Specific heat and heat.
Answer
Correct option: C.
Heat and work.
Explanation:
As work done in raising temperature of a body is actually the heat supplied to the body, heat and work may be represented in the same unit.
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MCQ 71 Mark
Water equivalent of a body is measured in:
  • ✓
    $Kg$
  • B
    Calorie
  • C
    Kelvin
  • D
    $m^3$
Answer
Correct option: A.
$Kg$
Since water equivalent of a body is the mass of the water having the same heat capacity as the given body, the water equivalent is measured in kilogram.
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MCQ 81 Mark
The specific heat capacity of a body depends on:
  • A
    The heat give.
  • B
    The temperature raised.
  • C
    The mass of the body.
  • ✓
    The material of the body.
Answer
Correct option: D.
The material of the body.
Explanation:
Heat capacity of a body is due to their material properties. Due to different molecular structures, different bodies have a different capacity to absorb heat. Therefore, specific heat of a body depends on the material of the body.
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MCQ 91 Mark
Heat and work are equivalent. This means:
  • A
    When we supply heat to a body we do work on it.
  • B
    When we do work on a body we supply heat to it.
  • ✓
    The temperature of a body can be increased by doing work on it.
  • D
    A body kept at rest may be set into motion along a line by supplying heat to it.
Answer
Correct option: C.
The temperature of a body can be increased by doing work on it.
Explanation:
According to the statement "heat and work are equivalent", heat supplied to the body increases its temperature. Similarly, work done on the body also increases its temperature.
For example: If work is done on rubbing the hands against each other, the temperature of the hands increases. So, we can say that heat and work are equivalent.
When heat is supplied to a body, we do not do work on it. When we are doing work on a body, it does not mean we are supplying heat to the body. Also, a body at rest cannot be set in motion along a line by supplying heat to it. So, these statements do not justify the equivalence of heat and work.
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