Questions

The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton's third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.

Steel is not a compound or element. Steel is an alloy of iron and carbon and other elements and hence it is a mixture. Because of its high tensile strength and low cost, it is a major component used in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons.

First Generation  Vacuum Tubes (1940-1956)

The first computer systems used vacuum tubes for circuitry and magnetic drums for memory

Padmalaya Nanda from Odisha will represent India at the 2017 Little Miss Universe beauty pageant competition, which is scheduled to be held in Georgia, United States from May 31. She will compete against 15 other contestants from around the world for the title of Little Miss Universe. Beside this, she will also lead India in the 2017 Little Miss World contest in Greece.