Which of the following elements reacts with water?

Which of the following is true for diamond?

$A$ $1 \ L$ flask is full of brown bromine vapour. The intensity of the brown colour of the vapour will not decrease appreciably on adding which of the following to the flask?

Give uses of carbon dioxide.

Explain the following reactions:
$(a)$ Silicon is heated with methyl chloride at high temperature in the presence of copper.
$(b)$ Silicon dioxide is treated with hydrogen fluoride.
$(c)$ $CO$ is heated with $ZnO$.
$(d)$ Hydrated alumina is treated with aqueous $NaOH$ solution.

The formula of Feldspar is: