Mole Concept & Stiochiometry
Single Option Correct
1. A 0.500 g sample of Magnetite ore (impure Fe3O4) is treated so that the iron is precipitated as Fe - III
hydroxide. The precipitate is heated and converted to 0.4980 g Fe2O3. What is the percentage of Fe3O4 in
the ore? (Fe - 56)
(A) 69.0 % (B) 96.3 % (C) 99.6 % (D) 35.0 %
2. Elements X and Y can combine to form two different compounds. If 1.60 g of X reacts with exactly 1.60 g
of Y, the compound produced has formula XY. However, under different conditions, 2.40 g of X will
react with 1.60 g of Y to form a second compound, whose empirical formula is
(A) X3Y4 (B) X4Y3 (C) XY3 (D) X3Y2
3. If 80.00 g of X combines with 1.5 × 1023 atoms of Y to form X2Y without any of either element
remaining, what is the atomic weight of X?
(A) 20 (B) 40 (C) 120 (D) 160
4. A metal sulphate is isomorphous with CaSO4.2H2O and contains 10% S. Atomic weight of the metal is
(Ca = 40)
(A) 108 (B) 188 (C) 94 (D) 208
5. If x grams of a metal forms y gram of the metal chloride, equivalent weight of the metal is
yx 35.5 y 35.5 x x
(A) (B) (C) (D)
35 .5 x y x yx 35.5( y x )
6. If x g of an unknown metal combines with y g of oxygen to form an oxide, the equivalent weight of the metal
in this reaction is
x 8y 8x y
(A) (B) (C) (D)
8y x y 8x
7. 0.795 g of an oxide of metal lost 20.12 % of its weight when heated in a current of pure and dry hydrogen
and was completely reduced to metallic state. What is the equivalent weight of metal?
(A) 40 (B) 32 (C) 28 (D) 16
8. 0.54 g of pure silver was dissolved in nitric acid and the solution was treated with slight excess of sodium
chloride solution. It formed 0.7175 g of silver chloride. Calculate the equivalent weight of silver.
(A) 108 (B) 216 (C) 59 (D) 54
Multiple Option Correct
9. If a non-conventional scale of amu is defined as (1 / 16)th part by weight of an atom of C-12 isotope, which
of the following is (are ) the correct atomic weight on this newly defined scale of amu? (Conventional
atomic weight : Al = 27, Ca = 40, Fe = 56, Ti = 48)
(A) Al = 36 (B) Ca = 53.33 (C) Fe = 74.66 (D) Ti = 64
10. Which of the following is (are) equivalent to 1.0 u?
(A) (1 / 24) × wt. of an atom of Mg(At. wt. of Mg = 24)
(B) (1 / 18) × wt. of a molecule of H2O (Mol. wt. of H2O = 18)
(C) (1 / 22) × wt. of one molecule of CO2 (Mol. wt. of CO2 = 44)
(D) (1 / 34) × wt. of one molecule of NH3 (Mol. wt. of NH3 = 17)
11. An oxide of nitrogen has 30.43% nitrogen (At.wt. of N = 14) and its one molecule weighs
1.527 × 10–22 g. Which of the following statement regarding the oxide is (are) true?
(A) Its empirical formula is N2O (B) Its empirical formula is NO2
(C) Its molecular formula is N2O4 (D) Its molecular formula is N4O2
Integer Answer Type
12. 1 gm of metal nitrate gave 0.86 g of metal sulphate. Calculate the equivalent weight of metal?
[Divide answer by 19]
13. 2 g of metal in H2SO4 gives 4.51 g of metal sulphate. The specific heat of metal is 0.057 Cal/g. Calculate
atomic weight of metal. [Divide answer by 23]
14. 1.878 gm of MBrx, when heated with HCl gas, was converted to MClx weighing 1g. The specific heat of
metal is 0.14 Cal/g. Calculate molecular weight of metal bromide. [Divide answer by 95]
Column Matching Type
15. Match the following compounds with their equivalent weights, and choose the correct code given below:
Compound EW
(A) Na3PO4 : Na3PO4 + 2HCl NaH2PO4 + 2NaCl p. 51.67
(B) Ca3(PO4)2 : CaCl2 + Na3PO4 Ca3 (PO4)2 + NaCl q. 63
(C) Na2CO3 : Na2CO3 + HClO4 NaHCO3 + NaClO4 r. 82
(D) H2C2O4.2H2O:H2C2O4+ CaO CaC2O4 + H2O s. 106
