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41. The process in which no heat enters or leaves the system is termed as?
A. Isobaric
B. Adiabatic
C. Isochoric
D. None
ANSWER:B
SOLUTION :The process in which no heat enters or leaves a system is called an adiabatic process. In an adiabatic process, energy is only transferred to the surroundings as work.
42. Water is usual as coolant in the radiator of a car engine because it ?
A. Has low boiling point
B. Has low density
C. Has high specific heat
D. None
ANSWER:C
SOLUTION:Water is used as a coolant in a car engine’s radiator because it has a high specific heat capacity of 4.186 J/g-K. This means that water can absorb more energy per degree change than other substances, which helps cool the system. Water also maintains the same temperature for a longer period.
43. Adding salt to vegetables takes less time to cook because?
A. Boiling point of water increases
B. Boiling point of water decreases
C. The secret heat of water evaporation increases
D. None
ANSWER:A
SOLUTION:Adding salt to water increases its boiling point, which can make vegetables cook faster. The boiling point of water increases by about 0.5°C for every 58 grams of salt dissolved per kilogram of water.
44. What is the reason for clay buildings being colder in summer & hotter in winter than brick buildings?
A. Raw soil is a bad driver
B. Raw soil is insulated
C. Raw soil is a good conductor
D. None
ANSWER:B
SOLUTION:Clay buildings are colder in the summer and warmer in the winter than brick buildings because clay is a poor conductor of heat. In the summer, the outside temperature is higher than the inside temperature of a clay building, so it feels cooler. In the winter, the outside temperature is lower than the inside temperature of a clay building, so it feels warmer
45. At which temperature does the water boil on the hills?
A. 1000C
B. Below 10000C
C. More than 10000C
D. None
ANSWER:B
SOLUTION:Water boils at a temperature below 1000°C on hills because atmospheric pressure decreases with altitude. For every 500 ft increase in elevation, the boiling point of water decreases by about 0.5°C. For example, at an elevation of 8,000 ft, water boils at 198°F (92°C).
46. Transfer of heat convection takes place in ?
A. Solid & vacuum
B. Solid & liquid
C. Gases & liquids
D. None
ANSWER:C
SOLUTION :The correct answer is In gas and liquid. Convection is the process of heat transfer by the movement of molecules in fluids like gas and liquid.
47. Expansion during heating?
A. Increases the weight of the material
B. Occurs only in solids
C. Decreases the density of the material
D. None
ANSWER:C
SOLUTION:Now, if we take an example of volumetric expansion, then we can say that on heating a substance the volume of the substance will increase but the mass will be constant. This results in a decrease in the density of the substance.
48. Which of the following substances has greatest specific heat?
A. Water
B. Copper
C. Iron
D. None
ANSWER:A
SOLUTION: water has the highest specific heat capacity.
49. Which is the fastest mode of heat loss?
A. Conduction
B. Radiation
C. Convection
D. None
ANSWER:B
SOLUTION: Radiation is the fastest mode of heat transfer because it travels at the speed of light and doesn’t require a medium to transfer heat. Radiation transfers heat in the form of electromagnetic waves and can even transfer energy in a vacuum.
50. Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of ?
A. Radiation & convection only
B. Conduction & convection only
C. Convection only
D. None
ANSWER:B
SOLUTION:In this case, since the heat energy is being transferred from the heater coil to the cooking vessel, which are both solid objects, convection alone cannot be the process of heat transfer. Option 2 states that the transfer of heat energy takes place through conduction and convection only.