For a chemical reaction A $$\to$$ B, it was found that concentration of B is increased by 0.2 mol L^$$-$$ in 30 min. The average rate of the reaction is ____________ $$\times$$ 10^$$-$$1 mol L^$$-$$1 h^$$-$$1. (in nearest integer)

The number of significant figures in 0.00340 is ____________.

Assuming that Ba(OH)₂ is completely ionised in aqueous solution under the given conditions the concentration of H₃O⁺ ions in 0.005 M aqueous solution of Ba(OH)² at 298 K is ______________ $$\times$$ 10^$$-$$12 mol L^$$-$$1. (Nearest integer)

0.8 g of an organic compound was analyzed by Kjeldahl's method for the estimation of nitrogen. If the percentage of nitrogen in the compound was found to be 42%, then ______________ mL of 1 M H₂SO₄ would have been neutralized by the ammonia evolved during the analysis.