21203.1.0 g of magnesium is burnt with 0.56 g O2 in a closed vessel. Which reactant is left in excess and how much? (At. wt. Mg = 24; O = 16)
Mg, 0.16 g
O2, 0.16 g
Mg, 0.44 g
O2, 0.28 g
21204.The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is
7 : 32
1 : 8
3 : 16
1 : 4
21205.The volume of oxygen evolved at STP, by decomposition of 0.68 g ‘20 volume’ hydrogen peroxide solution, is
2.24 mL
22.4 mL
224 mL
2240 mL
21206.The oxide of a metal contains 40% of oxygen. The valency of metal is 2. What is the atomic weight of the metal?
24
13
40
36
21207.Concentrated aqueous sulphuric acid is 98% H2SO4 by mass and has a density of 1.80 g.mL–1. Volume of acid required to make 1 litre of 0.1 M H2SO4 solution is:
5.55 mL
11.10 mL
16.65 mL
22.20 mL
21208.What volume of Hydrogen gas, at 273 K and 1 atm pressure will be consumed in obtaining 21.6 g of elemental boron (Atomic mass = 10.8) from the reduction of boron trichloride by Hydrogen?
89.6 L
67.2 L
44.8 L
22.4 L
21209.A gaseous hydrocarbon gives upon combustion 0.72 g of water and 3.08 g of CO2. The empirical formula of the hydrocarbon is:
C2H4
C3H4
C6H5
C7H8
21210.If Avogadro number NA, is changed from 6.022 × 1023 mol–1 to 6.022 × 1020 mol–1, this would change
The ratio of chemical species to each other in a balanced equation
The ratio of elements to each other in a compound
The definition of mass in units of grams
The mass of one mole of carbon
21211.An element, X has the following isotopic composition:
200X : 90%
199X : 8.0%
202X : 2.0%
The weighted average atomic mass of the naturally-occurring element X is closest to:
200X : 90%
199X : 8.0%
202X : 2.0%
The weighted average atomic mass of the naturally-occurring element X is closest to:
199 amu
200 amu
201 amu
202 amu