Questions

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.

bullet proof material is made up of polymer Poly carbonates.

Silicon carbide is used in Cutting very hard substances.

Galton's whistle is also called as Dogs whistle or silent whistle, is a type of whistle that emits sound in the ultrasonic range, which people cannot hear but some other animals can, including dogs and domestic cats, and is used in their training.

Autocorrect was originally designed to replace Misspelled words. Its purpose is as part of the spell checker to correct common spelling or typing errors, saving time for the user. It is commonly found in word processors and text editing interfaces for smartphones, computers, etc.