Questions

Tractor was the single most important invention to farmers.

Cotton Gin was invented by Eli Whitney in 1793, which is used to separate cotton seeds from cotton fiber.

Hence, it was an important invention because it dramatically reduced the amount of time it took to separate cotton seeds from cotton fiber.

The country Brazil is the largest producer of sugarcane in the world.

Electrical discharge machining (EDM), also known as spark machining, spark eroding, burning, die sinking, wire burning or wire erosion, is a manufacturing process whereby a desired shape is obtained by using electrical discharges.

No work done as there is no external external pressure in free expansion. 

Hence, Work done in a free expansion process is Zero.

Bicycle is a compound machine in the above given options. A compound machine is a machine that is formed by two or more simple machines.

Attribution theory was designed to account for how people explain others' behavior. It is a theory in psychology states that the attributions people make about events and behavior can be classed as either internal or external. In an internal, or dispositional, attribution, people infer that an event or a person's behavior is due to personal factors such as traits, abilities, or feelings.