The number of terminal oxygen atoms present in the product B obtained from the following reaction is _____________.

FeCr₂O₄ + Na₂CO₃ + O₂ $$\to$$ A + Fe₂O₃ + CO₂

A + H⁺ $$\to$$ B + H₂O + Na⁺

An acidified manganate solution undergoes disproportionation reaction. The spin-only magnetic moment value of the product having manganese in higher oxidation state is _____________ B.M. (Nearest integer)

Kjeldahl's method was used for the estimation of nitrogen in an organic compound. The ammonia evolved from 0.55 g of the compound neutralised 12.5 mL of 1 M H₂SO₄ solution. The percentage of nitrogen in the compound is _____________. (Nearest integer)

Observe structures of the following compounds

The total number of structures/compounds which possess asymmetric carbon atoms is ______________.