1
IIT-JEE 1983
Subjective
+5
-0
The density of a 3 M Sodium thiosulphate solution (Na2S2O3) is 1.25 g per ml. Calculate

(i) the percentage by weight of sodium thiosulphate,

(ii) the mole fraction of sodium thiosulphate and

(iii) the molalities of Na+ and $$S_2O_3^{-2}$$ ions
2
IIT-JEE 1983
Subjective
+4
-0
4.08 g of a mixture of BaO and an unknown carbonate MCO3 was heated strongly. The residue weighed 3.64 g. This was dissolved in 100 ml of 1 N HCl. The excess acid required 16 ml of 2.5 N NaOH solution for complete neutralization. Identify the metal M. (At wt. H = 1, C = 12, O = 16, Cl = 35.5, Ba = 138)
3
IIT-JEE 1982
Subjective
+4
-0
Hydroxylamine reduces iron (III) according to the equation:

2NH2OH + 4Fe3+ $$\to$$ N2O(g) $$ \uparrow $$ + H2O + 4Fe2+ + 4H+

Iron (II) thus produced is estimated by titration with a standard permanganate solution. The reaction is :

$$MnO_4^-$$ + 5Fe2+ + 8H+ $$\to$$ Mn2+ + 5Fe3+ + 4H2O

A 10 ml sample of hydroxylamine solution was Diluted to 1 litre. 50 ml of this diluted solution was boiled with an excess of iron (III) solution. The resulting solution required 12 ml of 0.02 M KMnO4 solution for complete oxidation of iron (II). Calculate the weight of hydroxylamine in one litre of the original solution. (H = 1, N = 14, O = 16, K =39, Mn = 55, Fe = 56)
4
IIT-JEE 1981
Subjective
+3
-0
A 1.00 gm sample of H2O2 solution containing X percent H2O2 by weight requires X ml of a KMnO4 solution for complete oxidation under acidic conditions. Calculate the normality of the KMnO4 solution.
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