1. During change of state which of the following is constant [ ]
a) Heat b) Volume c) Temperature d) None
2. When two pieces of ice are pressed together, they combine to form one single piece. This process
is called [ ]
a) Freezing b) Regelation c) Combination d) Sublimation
3. At Triple point [ ]
a) only solid and liquid states exist in equilibrium
b) only solid and gas states exist in equilibrium
c) only liquid and gas state exist in equilibrium
d) all solid, liquid and gas exist together in equilibrium
4. Amount of heat corresponding to 1 calorie of heat is [ ]
a) 4.2 joule b) 4.2 × 1010 joule c) 42 joule d) 4.2 × 107
joule
5. Among the following the substance which have maximum specific heat value is [ ]
a) Copper b) Ice c) Water d) Mercury
Thermal capacity of a body is numerically equal to [ ]
a) specific heat b) water equivalent c) molar specific heat d) all the above
6. A fan produces a feeling of comfort because [ ]
a) A fan supplies cool air b) Due to evaporation of sweat
c) Fan cools the air d) Fan increases the humidity in air
7. The principle of calorimetry represents the law of conservation of [ ]
a) Mass b) Heat energy c) Momentum d) Temperature
Answers
1. c) temperature
The temperature remains constant during the change of state because the heat energy which is supplied to change the state of matter is used in breaking the intermolecular forces and other attractive forces. Hence the temperature remains constant as all the heat is used up and no external heat is released or absorbed
2. a) The melting point of ice is lowered on increasing the pressure. When two blocks of ice are pressed against each other, the pressure applied on the blocks of ice increases and the melting point increases. Thus the two blocks of ice fuse together.
3. D) In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium
4. a) approximately 4.2 joules
The calorie was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° Celsius. Since 1925 this calorie has been defined in terms of the joule, the definition since 1948 being that one calorie is equal to approximately 4.2 joules.
5. c) Water
Water has the highest specific heat capacity of any liquid.
∆ d) We can see that thermal capacity and water equivalent of a body are numerically equal, therefore their ratio is equal to one
6. b) fan produces a feeling of comfort because our perspiration or sweating evaporates rapidly. Our body try to cool ourselves releasing sweat through pores of skin. And when we sit under the fan the sweat evaporates due to directed air upon us making our body cool as evaporation is the cooling process.
7. b) It is based on the law of conservation of energy, which says that energy is neither created nor destroyed during a chemical reaction. In calorimetry, this means that the heat gained by the water in the calorimeter must have been released by the sample or the reaction taking place in the calorimeter
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