Correct Answer: Option 2 – Nuclear fusion

Nuclear fusion is a process, where like charged atomic nuclei join together to form heavier nucleus.

this is marked by release of energy, by emission of light.

Incorrect Options

Convection is one of the major modes of heat transfer, by movement of molecules. This can happen in liquids or gases.

Insolation is the amount of solar radiation or electromagnetic radiation from the sun on the surface of earth

Radioactive decay refers to loss of energy by nucleus by emitting radiation.

Correct Answer: Option 4 – Radiation

Radiation is the process of release of energy when a body travels from one medium through another and hence absorbed

Incorrect Options

Conduction is a process of heat transfer from a hotter surface or a body to a coller surface or a body, due to temperature difference

Reflection is abrupt change in the direction of propagating wave striking the boundary between different mediums

Refraction is the change in direction of a wave passing from one medium to another caused by its change in velocity

Correct Answer: Option 2 – Calcite will be scratched by a copper penny

According to the diagram the hardness of calcite and copper penny are similar. Hence, option 2 is the correct answer.

A fingernail will not scratch calcite but can scratch gypsum since the hardness of fingernail lies between that of calcite and gypsum. Hence, option 1 is incorrect.

The mineral apatite cannot scratch topaz since topaz is harder than apatite. Hence, option 3 is incorrect.

Correct Answer: Water is also commonly expressed as 539.423 calories per gram – enthalpy of vaporization or latent heat of vaporization