This set of Fruits Processing Multiple Choice Questions & Answers (MCQs) focuses on “Thermal Properties”.
1. What is the meaning of thermal properties?
a) Related to its conductivity of heat
b) Related to its radiation
c) Related to its absorption
d) Related to its adsorption
View Answer
Explanation: Thermal properties are those properties of a material which is related to its conductivity of heat. These properties are exhibited by a material when the heat is passed through it. Examples of thermal properties are specific heat, latent heat.
2. Which of the following is not a physical property of food?
a) Water activity
b) Moisture
c) Specific heat
d) Temperature
View Answer
Explanation: The amount of heat needed to raise the temperature of 1 gram of a substance 1 o C is called as specific heat. Water has a high specific heat capacity. Therefore, it takes more energy to increase the temperature of water compared to other substances.
3. Does thermal conductivity depend on thickness?
a) True
b) False
View Answer
Explanation: Thermal conductivity is affected by changes in thickness and orientation. The temperature also has an effect on the overall magnitude. Due to increase in the material temperature i, the internal particle velocity also increases and results in increase in thermal conductivity.
4. Which of the following factor does not influences thermal conductivity?
a) Size
b) Temperature
c) Density
d) Moisture content
View Answer
Explanation: Thermal conductivity will not differ with the dimensions of a material. It is dependent on the temperature, the density and the moisture content of the material. It also depends on the properties of the material, and the path length that the heat follows.
5. Which of the following are the types of latent heat??
a) Latent heat of fusion and latent heat of vaporization
b) Latent heat of vaporization and latent heat of sublimation
c) Latent heat of fusion and latent heat of sublimation
d) Latent heat of fusion, latent heat of vaporization and latent heat of sublimation
View Answer
Explanation: The enthalpy change of any amount of constituent when it melts is called as the latent heat of fusion. The heat required to change one mole of liquid at its boiling point under standard atmospheric pressure is called as the latent heat of vaporization. At a particular temperature, the amount of heat required to convert a unit mass of solid into gas is called as the latent heat of sublimation.
6. Which material has highest thermal diffusivity?
a) Silver
b) Aluminum
c) Plastic
d) Nickel
View Answer
Explanation: Silver has highest thermal diffusivity. A material with a high thermal diffusivity is a good diffuser of thermal energy. Plastic has lowest thermal diffusivity. A material with a low thermal diffusivity is much slower at diffusing thermal energy.
7. What happens when thermal equilibrium is reached?
a) State of a system in which all parts are at the same temperature
b) State of a system in which all parts are at the same latent heat
c) State of a system in which all parts are at the same specific heat
d) State of a system in which all parts are at the same thermal conductivity
View Answer
Explanation: Thermal equilibrium is defined as the state of a system in which all parts are at the same temperature. During the process of reaching thermal equilibrium, heat is transferred between the objects normally higher temperature to lower temperature. It is proportional to the average kinetic energy of atoms and molecules in a system.
8. Can latent heat become zero?
a) True
b) False
View Answer
Explanation: Latent heat is the heat or energy in the hidden form. It can be given or extracted to change the state of the substance without changing the temperature. The latent heat of vaporization will become zero when the temperature or pressure equals zero.
9. Are these statements about the latent heat true?
Statement 1: Heat absorbed or released as the result of a phase change is called latent heat.
Statement 2: There is no change in the kinetic energy of particles in the material during phase change.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: Latent heat is defined as the amount of heat absorbed or released as the result of a phase change is called latent heat. There will be no temperature change during a phase change, thus there is no change in the kinetic energy of the particles. The energy released derives from the potential energy stored in the bonds among the particles.
10. What is the latent heat of fusion of ice?
a) 3.33 x 105J/kg
b) 2257kJ/kg
c) 2.295kJ/mol
d) 59.229kJ/mol
View Answer
Explanation: The heat of fusion for ice or water is Lf = 3.33 x 105J/kg. Latent heat of steam at atmospheric pressure is 2257 kJ/kg. Latent heat of fusion of mercury is 2.295 kJ/mol. The latent heat of vaporization of mercury is 59.229kJ/mol.
Sanfoundry Global Education & Learning Series – Fruits Processing.
To practice all areas of Fruits Processing, here is complete set of 1000+ Multiple Choice Questions and Answers.
