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?
Answer
(C)
12.15
2
The largest number of molecules is in
Answer
(A)
32 g of water
3
2.76 g of silver carbonate on being strongly heated yields a residue weighing
Answer
(A)
2.16 g
4
The total number of electrons is one molecule of carbon dioxide is
Answer
(A)
22
5
A gaseous mixture contains oxygen and nitrogen in the ratio of 1 : 4 by weight. Therefore the ratio of their no of molecules is
Answer
(C)
7 : 32
6
(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.
Answer
(B)
0.437
7
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.
Answer
(C)
C2H4
8
In the analysis of 0.5 g sample feldspar, a mixture of chlorides of sodium and potassium is obtained which weighs 0.1180g. Subsequent treatment of mixed chlorides with silver nitrate gives 0.2451 g of silver chloride. What is the percentage of sodium oxide and potassium oxide in feldspar.
Answer
(A)
Na₂O = 3.58%, K₂O = 10.62%
9
The number of neutrons in dipositive zinc ion with mass number 70 is
Answer
(D)
40
10
The compound which contains both ionic and covalent bonds is
Answer
(C)
KCN
11
The octet rule is not valid for the molecule
Answer
(D)
CO
12
Account for the following : Limit your answer to two
sentences.
"Atomic weights of most of the elements are fractional."
Answer
(C)
The atomic weights are average weights of the element which accounts for the relative abundance of its isotopes, thus yielding fractional values.
13
A white amorphous powder (A) on heating yields a
colourless, non-combustible gas (B) and a solid (C).
The latter compound assumes a yellow colour on heating
and changes to white on cooling. (C) dissolves in dilute
acid and the resulting solution gives a white precipitate
on adding K4Fe(CN)6
solution.
(A) dissolves in dilute HCl with the evolution of gas,
which is identical in all respects with (B). The gas (B)
turns lime water milky, but the milkiness disappears with
the continuous passage of gas. The solution of (A), as
obtained above, gives a white precipitate (D) on the
addition of excess of NH4OH and passing H2S. Another
portion of the solution gives initially a white precipitate
(E) on the addition of sodium hydroxide solution, which
dissolves on further addition of the base. Identify the
compounds (A), (B), (C), (D) and (E).
Answer
(A)
A - ZnCO3, B - CO2, C - ZnO, D - ZnS, E - Zn(OH)2
14
The precipitation of second group sulphides in qualitative
analysis is carried out with hydrogen sulphide in the presence
of hydrochloric acid but not in nitric acid. Explain.
Answer
(C)
Nitric acid oxidizes H2S to elemental sulfur, preventing sulfide precipitation.
