Questions

The size of gear is usually specified by pitch circle diameter.

Based on conventionality in deriving energy, energy sources could be classified as

Conventional ::

coal, oil, hydro, nuclear, etc... sources which can be used up or exhaustible.

(and)

Non - conventional ::

solar, wind, tidal, geothermal, biogas, etc... sources which are not exhausted.

Among the given options, Geothermal energy is the alternative energy source among all the choices that are given in the question, that is exhaustible.

The given matching is about the policies and acts names and in which year they took place.

Here Green Revolution - 1991 is given and which is not TRUE. It took place in between 1960 - 1980.

In music, a fugue is a contrapuntal compositional technique in two or more voices, built on a subject that is introduced at the beginning in imitation and which recurs frequently in the course of the composition. 

Hence, the main theme of a fugue is called the subject.

The no of entities participating in relation is called Degree of relationship

Silicon carbide is used in Cutting very hard substances.