Matter in Our Surroundings — Science STD 9 — Question

On the earth, a stone is thrown from a height in a direction parallel to the earth’s surface while another stone is simultaneously dropped from the same height. Which stone would reach the ground first and why?

Under what conditions heat can be given to a substance without raising its temperature?

Define:
Green manure.

In a chemical compound calcium sulphate:
Name the resulting compound.

Calculate the molecular mass of ethanoic acid, CH₃COOH.
(Atomic masses: C = 12u; H = 1u; O = 16u)

Name the device or machines which convert:
Light energy into heat energy.

What is the common name of '1kWh' of electrical energy’?

What name has been given to the elements required by plants in:

1. Smaller amount.
2. Larger amount.