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 ______________.

C₆H₁₂O₆ $$\buildrel \text{Zymase} \over \longrightarrow $$ A $$\mathrel{\mathop{\kern0pt\longrightarrow} \limits_\Delta ^\text{NaOI}} $$ B + CHI₃

The number of carbon atoms present in the product B is _______________.

The probability that a randomly chosen 2 $$\times$$ 2 matrix with all the entries from the set of first 10 primes, is singular, is equal to :