Modern refrigerators usually use a refrigerant called HFC-134a (1,1,1,2-Tetrafluoroethane), which does not deplete the ozone layer, instead of Freon. Freon used to be the most common refrigerant till the 1980s; however, its use has declined since the 1990s because it comes under Chlorofluorocarbon (CFC). Ammonia was also used a a common refrigerant in old refrigerators. However, Freon still remains the most commonly used refrigerant. Hydrochlorofluorocarbon (HCFC), is a type of refrigerator coolant used in newer refrigerator models. The types used today include HFC-134a, HCFC-142b and HCFC-22.

Correct Option: C

Modern refrigerators usually use a refrigerant called HFC-134a (1,1,1,2-Tetrafluoroethane), which does not deplete the ozone layer, instead of Freon. Freon used to be the most common refrigerant till the 1980s; however, its use has declined since the 1990s because it comes under Chlorofluorocarbon (CFC). Ammonia was also used a a common refrigerant in old refrigerators. However, Freon still remains the most commonly used refrigerant. Hydrochlorofluorocarbon (HCFC), is a type of refrigerator coolant used in newer refrigerator models. The types used today include HFC-134a, HCFC-142b and HCFC-22.

The decibel (dB) is the unit used to measure the intensity of sound or noise level. It is given in terms of a logarithmic function of a ratio of power intensities. One decibel is one tenth of one bel, named in honor of Alexander Graham Bell who was the inventor of the telephone and phonograph.

Correct Option: A

The decibel (dB) is the unit used to measure the intensity of sound or noise level. It is given in terms of a logarithmic function of a ratio of power intensities. One decibel is one tenth of one bel, named in honor of Alexander Graham Bell who was the inventor of the telephone and phonograph.

An amplifier is an electronic device that increases the voltage, current, or power of a signal.Generally transistors are active devices that can be used with discrete components to amplify voltage, power or both depending upon the configuration.

Correct Option: D

An amplifier is an electronic device that increases the voltage, current, or power of a signal.Generally transistors are active devices that can be used with discrete components to amplify voltage, power or both depending upon the configuration.

The process of heat transfer from one place to another place without the movement of particles is called conduction Example:Heat transfer through Metal rods. On the contrary, convection is the process by which heat is transmitted through a substance from a point to another due to the bodily motion of the heated particles of the substance. The fluids (liquids and gases) are heated by this process.

Correct Option: B

The process of heat transfer from one place to another place without the movement of particles is called conduction Example:Heat transfer through Metal rods. On the contrary, convection is the process by which heat is transmitted through a substance from a point to another due to the bodily motion of the heated particles of the substance. The fluids (liquids and gases) are heated by this process.

Solar energy, in the form of heat and light, travels from the sun to Earth through the process of radiation. This way, energy can be transferred through empty space without relying on matter. This radiation is largely visible as light to the naked eye, although it also includes ultraviolet and infrared radiation as well.

Correct Option: C

Solar energy, in the form of heat and light, travels from the sun to Earth through the process of radiation. This way, energy can be transferred through empty space without relying on matter. This radiation is largely visible as light to the naked eye, although it also includes ultraviolet and infrared radiation as well.