The density of NaOH solution is 1.2 g cm^$$-$$3. The molality of this solution is _____________ m. (Round off to the Nearest Integer)

[Use : Atomic mass : Na : 23.0 u, O : 16.0 u, H : 1.0 u, Density of H₂O : 1.0 g cm^$$-$$3]

The number of significant figures in 0.00340 is ____________.

When 10 mL of an aqueous solution of Fe²⁺ ions was titrated in the presence of dil H₂SO₄ using diphenylamine indicator, 15 mL of 0.02 M solution of K₂Cr₂O₇ was required to get the end point. The molarity of the solution containing Fe²⁺ ions is x $$\times$$ 10^$$-$$2 M. The value of x is __________. (Nearest integer)

Consider the complete combustion of butane, the amount of butane utilized to produce 72.0 g of water is ___________ $$\times$$ 10^$$-$$1 g. (in nearest integer)