1
IIT-JEE 1980
Subjective
+4
-0
(a) One litre of a sample of hard water contains 1 mg of CaCl2 and 1 mg of MgCl2. Find the total hardness in terms of parts of CaCO3 per 106 parts of water by weight.

(b) A sample of hard water contains 20 mg of Ca++ ions per litre. How many milli-equivalent of Na2CO3 would be required to soften 1 litre of the sample?

(c) 1 gm of Mg is burnt in a closed vessel which contains 0.5gm of O2.
      (i) Which reactant is left in excess?
      (ii) Find the weight of the excess reactants.
      (iii) How many milliliters of 0.5N H2SO4 will dissolve the residue in the vessel?
2
IIT-JEE 1979
Subjective
+2
-0
4.215 g of a metallic carbonate was heated in a hard glass tube and the CO2 evolved was found to measure 1336 ml at 27oC and 700 mm pressure. What is the equivalent weight of metal?
3
IIT-JEE 1979
Subjective
+4
-0
(a). 5.5 g of a mixture FeSO4.7H2O and Fe2(SO4)3.9H2O requires 5.4 ml of 0.1 N KMnO4 solution for complete oxidation. Calculate the number of gram mole of hydrated ferric sulphate in the mixture.

(b). The vapour density (hydrogen = 1) of a mixture consisting of NO2 and N2O4 is 38.3 at 26.7oC. Calculate the number of moles of NO2 in 100 g of the mixure.
4
IIT-JEE 1979
Subjective
+4
-0
5 ml of a gas containing only carbon and hydrogen were mixed with an excess of oxygen (30 ml) and the mixture exploded by means of an electric spark. After the explosion, the volume of the mixed gases remaining was 25 ml. On adding a concentrated solution of potassium hydroxide, the volume further diminished to 15 ml of the residual gas being pure oxygen. All volumes have been reduced to N.T.P. Calculate the molecular formula of the hydrocarbon gas.
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