Consider the elements ₈B, ₂₀A. What type of bond will be formed when element B and A react with each other. Also find out in which group, A and B elements are present in the periodic table.

(a) List any two uses of ammonia.

(b) Give the balanced equations for the following conversions

1. Ammonia solution to an amphoteric hydroxide
2. Ammonia to brown gas

The empirical formula and molecular mass of a compound are CH₂O and 180 g respectively. What will be the molecular formula of the compound?

Choose the most appropriate option from the following list of elements which fit in the description. Each option may be used only once.

[Aluminium, helium, carbon, phosphorous, sodium, potassium, argon, hydrogen]

(a) An element with variable (more than one) valency and stored in water.

(b) An element present in period 3 and group I of the periodic table.

(c) An element which is an inert gas with atomic number 2.