Which of the following is a mineral of sulfur?

Give the composition of the alloys brass and bronze.

What happens when:
$(i)$ $A$ piece of calcium is dropped in water.
$(ii)$ Sodium is kept exposed in air.
$(iii)$ Iron nail is dipped in copper sulphate solution.
$(iv)$ Potassium is dropped in cold water.
$(v)$ Carbon dioxide is compressed in water at high pressure.
Give chemical equations involved in all the above reactions and balance them.

Write true or false for the following statement:
Hydrogen gas is evolved when a metal reacts with nitric acid.

What is the molecular formula of sodium aluminate?

Which metal is used in thermometers?