The neutralization occurs when 10 mL of 0.1M acid 'A' is allowed to react with 30 mL of 0.05 M base M(OH)₂. The basicity of the acid 'A' is __________.

[M is a metal]

10.0 mL of 0.05 M KMnO₄ solution was consumed in a titration with 10.0 mL of given oxalic acid dihydrate solution. The strength of given oxalic acid solution is _________ $$\times$$ 10^$$-$$2 g/L.

(Round off to the nearest integer)

Dichromate ion is treated with base, the oxidation number of Cr in the product formed is ___________.

0.4 g mixture of NaOH, Na₂CO₃ and some inert impurities was first titrated with $${N \over {10}}$$ HCl using phenolphthalein as an indicator, 17.5 mL of HCl was required at the end point. After this methyl orange was added and titrated. 1.5 mL of same HCl was required for the next end point. The weight percentage of Na₂CO₃ in the mixture is ________. (Rounded off to the nearest integer)