11. On a linear temperature scale $$Y,$$ water freezes at $$ - {160^ \circ }Y$$ and boils at $$ - {50^ \circ }Y.$$ On this $$Y$$ scale, a temperature of $$340\,K$$ would be read as : (water freezes at $$273\,K$$ and boils at $$373\,K$$ )
A
$$ - {73.7^ \circ }Y$$
B
$$ - {233.7^ \circ }Y$$
C
$$ - {86.3^ \circ }Y$$
D
$$ - {106.3^ \circ }Y$$
Answer :
$$ - {86.3^ \circ }Y$$
12. Three liquids of equal volumes are thoroughly mixed. If their specific heats are $${s_1},{s_2},{s_3}$$ and their temperatures $${\theta _1},{\theta _2},{\theta _3}$$ and their masses $${m_1},{m_2},{m_3}$$ respectively , then the final temperature of the mixture is
A
$$\frac{{{s_1}{\theta _1} + {s_2}{\theta _2} + {s_3}{\theta _3}}}{{{m_1}{s_1} + {m_2}{s_2} + {m_3}{s_3}}}$$
B
$$\frac{{{m_1}{s_1}{\theta _1} + {m_2}{s_2}{\theta _2} + {m_3}{s_3}{\theta _3}}}{{{m_1}{s_1} + {m_2}{s_2} + {m_3}{s_3}}}$$
C
$$\frac{{{m_1}{s_1}{\theta _1} + {m_2}{s_2}{\theta _2} + {m_3}{s_3}{\theta _3}}}{{{m_1}{\theta _1} + {m_2}{\theta _2} + {m_3}{\theta _3}}}$$
D
$$\frac{{{m_1}{\theta _1} + {m_2}{\theta _2} + {m_3}{\theta _3}}}{{{s_1}{\theta _1} + {s_2}{\theta _2} + {s_3}{\theta _3}}}$$
Answer :
$$\frac{{{m_1}{s_1}{\theta _1} + {m_2}{s_2}{\theta _2} + {m_3}{s_3}{\theta _3}}}{{{m_1}{s_1} + {m_2}{s_2} + {m_3}{s_3}}}$$
13.
A water cooler of storage capacity 120 litres can cool water at a constant rate of $$P$$ watts. In a closed circulation system (as shown schematically in the figure), the water from the cooler is used to cool an external device that generates constantly $$3\, k W$$ of heat (thermal load). The temperature of water fed into the device cannot exceed $$30{\,^ \circ }C$$ and the entire stored 120 litres of water is initially cooled to $$10{\,^ \circ }C.$$ The entire system is thermally insulated. The minimum value of $$P$$ (in watts) for which the device can be operated for 3 hours is
(Specific heat of water is $$4.2\,kJ\,k{g^{ - 1}}{K^{ - 1}}$$ and the density of water is $$1000\,kg\,{m^{ - 3}}$$ )
A
1600
B
2067
C
2533
D
3933
Answer :
2067
14. $$300\,gm$$ of water at $${25^ \circ }C$$ is added to $$100\,g$$ of ice at $$0^ \circ C.$$ The final temperature of the mixture is
A
$$ - {\frac{5}{3}^ \circ }C$$
B
$$ - {\frac{5}{2}^ \circ }C$$
C
$${5^ \circ }C$$
D
$${0^ \circ }C$$
Answer :
$${0^ \circ }C$$
15. The latent heat of vaporization of a substance is always
A
greater than its latent heat of fusion
B
greater than its latent heat of sublimation
C
equal to its latent heat of sublimation
D
less than its latent heat of fusion
Answer :
greater than its latent heat of fusion
16.
$$10\,g$$ of ice cubes at $${0^ \circ }C$$ are released in a tumbler (water equivalent $$55\,g$$ ) at $${40^ \circ }C.$$ Assuming that negligible heat is taken from the surroundings, the temperature of water in the tumbler becomes nearly
$$\left( {L = 80\,cal/g} \right)$$
A
$${31^ \circ }C$$
B
$${22^ \circ }C$$
C
$${19^ \circ }C$$
D
$${15^ \circ }C$$
Answer :
$${22^ \circ }C$$
17. A $$5.0\,g$$ bullet (specific heat of material of bullet $$128\,J/k{g^ \circ }C$$ ) moving with a velocity of $$200\,m/s$$ enters a sand bag and stops. If the entire kinetic energy of the bullet is changed into heat energy that is added to the bullet, then the rise in the temperature of the bullet is
A
$${312.5^ \circ }C$$
B
$${156^ \circ }C$$
C
$${500^ \circ }C$$
D
$${624^ \circ }C$$
Answer :
$${156^ \circ }C$$
18. A lead bullet strikes against a steel plate with a velocity $$200\,m{s^{ - 1}}.$$ If the impact is perfectly inelastic and the heat produced is equally shared between the bullet and the target, then the rise in temperature of the bullet is (specific heat capacity of lead $$ = 125\,J\,k{g^{ - 1}}{K^{ - 1}}$$ )
A
$${80^ \circ }C$$
B
$${60^ \circ }C$$
C
$${160^ \circ }C$$
D
$${40^ \circ }C$$
Answer :
$${80^ \circ }C$$
19. In a water-fall the water falls from a height of $$100\,m.$$ If the entire $$K.E.$$ of water is converted into heat, the rise in temperature of water will be
A
$${0.23^ \circ }C$$
B
$${0.46^ \circ }C$$
C
$${2.3^ \circ }C$$
D
$${0.023^ \circ }C$$
Answer :
$${0.23^ \circ }C$$
20. Calorie is defined as the amount of heat required to raise temperature of $$1\,g$$ of water by $$1{\,^ \circ }C$$ and it is defined under which of the following conditions?
A
From $$14.5{\,^ \circ }C$$ to $$15.5{\,^ \circ }C$$ at $$760\,mm$$ of $$Hg$$
B
From $$98.5{\,^ \circ }C$$ to $$99.5{\,^ \circ }C$$ at $$760\,mm$$ of $$Hg$$
C
From $$13.5{\,^ \circ }C$$ to $$14.5{\,^ \circ }C$$ at $$76\,mm$$ of $$Hg$$
D
From $$3.5{\,^ \circ }C$$ to $$4.5{\,^ \circ }C$$ at $$76\,mm$$ of $$Hg$$
Answer :
From $$14.5{\,^ \circ }C$$ to $$15.5{\,^ \circ }C$$ at $$760\,mm$$ of $$Hg$$