1) The number of significant figures for the three numbers 161 cm, 0.161 cm, 0.0161 cm are:
a) 3, 4, and 5 respectively b) 3, 4, and 4 respectively c) 3, 3, and 4 respectively d) 3, 3, and 3 respectively
Answer: d) 3, 3, and 3
2) 0.24 g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H₂ = 0.089)
a) 95.93 b) 59.93 c) 95.39 d) 5.993
Answer: b) 59.93
3) The molecular weight of O₂ and SO₂ are 32 and 64 respectively. At 15°C and 150 mmHg pressure, 1 L of O₂ contains ‘N’ molecules. The number of molecules in 2L of SO₂ under the same conditions of temperature and pressure will be:
a) 2N b) N/2 c) N d) 4N
Answer: a) 2N
4) In the final answer of the expression, the number of significant figures is:
a) 1 b) 2 c) 3 d) 4
Answer: c) 3
5) An organic compound contains 78% (by wt.) carbon and the remaining percentage of hydrogen. The right option for the empirical formula of this compound is [At. wt. of C = 12, H = 1]:
a) CH b) CH₂ c) CH₃ d) CH₄
Answer: c) CH₃
6) The number of protons, neutrons, and electrons in , respectively, are:
a) 104, 71, and 71 b) 71, 71, and 104 c) 175, 104, and 71 d) 71, 104, and 71
Answer: d) 71, 104, and 71
7) Suppose the elements X and Y combine to form two compounds XY₂ and X₃Y₂. When 0.1 mole of XY₂ weighs 10 g and 0.05 mole of X₃Y₂ weighs 9 g, the atomic weights of X and Y are:
a) 40, 30 b) 60, 40 c) 20, 30 d) 30, 20
Answer: a) 40, 30
8) An organic compound contains carbon, hydrogen, and oxygen. Its elemental analysis gave C = 38.71% and H = 9.67%. The empirical formula of the compound would be:
a) CH₃O b) CH₂O
c) CHO d) CH₄O
Answer: a) CH₃O
9) 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:
a) 201 u b) 202 u c) 199 u d) 200 u
Answer: d) 200 u
10) Which of the following is isoelectronic?
a) CO₂, NO₂ b) NO₂, CO₂ c) CN⁻, CO d) SO₂, CO₂
Answer: c) CN⁻, CO
11) An organic compound containing C, H, and N gave the following results on analysis: C = 40%, H = 13.33%, N = 46.67%. Its empirical formula would be:
a) C₂H₇N₂ b) CHN c) CH₄N d) C₂H₇N
Answer: c) CH₄N
12) An organic compound contains C = 40%, O = 53.34%, and H = 6.60%. The empirical formula of the compound is:
a) CH₂O b) CHO c) CH₄O₂ d) C₂H₂O
Answer: a) CH₂O
13) Boron has two stable isotopes, 10B (19%) and 11B (81%). Calculate the average atomic weight of boron in the periodic table.
a) 10.8 b) 10.2 c) 11.2 d) 10.0
Answer: a) 10.8
14) While extracting an element from its ore, the ore is ground and leached with dilute KCN solution to form the soluble product potassium argento-cyanide. The element is:
a) Lead b) Chromium c) Manganese d) Silver
Answer: d) Silver
15) A metal oxide has the formula Z₂O₃. It can be reduced by hydrogen to give free metal and water. 0.1596 g of the metal oxide requires 6 mg of hydrogen for complete reduction. The atomic weight of the metal is:
a) 27.9 b) 159.6 c) 79.8 d) 55.8
Answer: d) 55.8
16) One mole of carbon atom weighs 12 g, the number of atoms in it is equal to:
a) 1.2 × 10²³ b) 6.022 × 10²² c) 12 × 10²² d) 6.022 × 10²³
Answer: d) 6.022 × 10²³
17) Which one of the following has the maximum number of atoms?
a) 1g of Mg(s) b) 1g of O₂(g) c) 1g of Li(s) d) 1g of Ag(s)
Answer: c) 1g of Li(s)
18) In which case is the number of molecules of water maximum?
a) 0.00224 L of water vapours at 1 atm and 273 K b) 0.18 g of water c) 18 mL of water d) 10⁻³ mol of water
Answer: c) 18 mL of water
19) If Avogadro’s number NAN_A is changed from 6.022 × 1023mol-1 to 6.022× 1020
mol-1, this would change:
a) The definition of mass in units of grams b) The mass of one mole of carbon c) The ratio of chemical species to each other in a balanced equation d) The ratio of elements to each other in a compound
Answer: b) The mass of one mole of carbon
The total number of valence electrons in 4.2 g of N³⁻ ion is (NA is the Avogadro’s number) a) 2.1 NA
b) 4.2 NA
c) 1.6 NA
d) 3.2 NA
Answer: c) 1.6 NA
21) How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M HNO₃? The concentrated acid is 70% HNO₃.
a) 45.0 g conc. HNO₃ b) 90.0 g conc. HNO₃ c) 70.0 g conc. HNO₃ d) 54.0 g conc. HNO₃
Answer: a) 45.0 g conc. HNO₃
22) 6.02×10206.02 × 10^{20} molecules of urea are present in 100 mL of its solution. The concentration of solution is:
a) 0.02 M b) 0.01 M c) 0.001 M d) 0.1 M
Answer: b) 0.01 M
23) The number of atoms in 0.1 mole of a triatomic gas is:
a) 6.022× 1022 b) 1.806× 1023 c) 3.600× 1023 d) 1.800×1022
Answer: b) 1.806× 1023
24) Volume occupied by one molecule of water (density = 1 g/cm³) is:
a) 9.0× 10-23 cm³ b) 6.023×10-23 cm³ c) 3.0 × 10-23 cm³ d) 5.5× 10-23 cm³
Answer: a) c) 3.0 × 10-23 cm³
25) The maximum number of molecules are present in:
a) 15 L of H₂ gas at STP b) 5 L of N₂ gas at STP c) 0.5 g of H₂ gas d) 10 g of O₂ gas
Answer: a) 15 L of H₂ gas at STP
26) Percentage of Se in peroxidase anhydrase enzyme is 0.5% by weight. The minimum molecular weight of peroxidase anhydrase enzyme is:
a) 1.568× 103 b) 15.68 c) 2.168× 104 d) 1.568 × 104
Answer: d) 1.568 × 104
27) The number of atoms in 4.25 g of NH₃ is approximately:
a) 4 × 10²³ b) 2 × 10²³ c) 1 × 10²³ d) 6 × 10²³
Answer: d) 6 × 10²³
28) Haemoglobin contains 0.33% of iron by weight. The molecular weight of haemoglobin is approximately 67200 g. The number of iron atoms (atomic weight of Fe is 56) present in one molecule of haemoglobin are:
a) 1 b) 6
c) 4 d) 2
Answer: c) 4
29) The number of moles of oxygen in 1 L of air containing 21% oxygen by volume, under standard conditions, is:
a) 0.0093 mole b) 2.10 moles c) 0.186 mole d) 0.21 mole
Answer: a) 0.0093 mole
30) The total number of valence electrons in 4.2 g of N₃⁻ ion is:
a) 2.1 Nₐ b) 4.2 Nₐ c) 1.6 Nₐ d) 3.2 Nₐ
Answer: c) 1.6 Nₐ
31) The number of gram molecules of oxygen in 6.02 × 10²⁴ molecules of CO₂ is:
a) 10 g molecules b) 5 g molecules c) 1 g molecule d) 0.5 g molecule
Answer: b) 5 g molecules
32) The number of oxygen atoms in 4.4 g of CO₂ is:
a) 1.2 × 10²³ b) 6 × 10²² c) 6 × 10²³ d) 12 × 10²³
Answer: a) 1.2 × 10²³
33) Ratio of Cₚ and Cᵥ of a gas ‘X’ is 1:4. The number of atoms of the gas ‘X’ present in 11.2 L of it at NTP will be:
a) 6.02 × 10²³ b) 1.2 × 10²³ c) 3.01 × 10²³ d) 2.01 × 10²³
Answer: a) 6.02 × 10²³
34) 1 cc of N₂O₂ at NTP contains:
a) 1.8 × 10²² atoms b) 6.02 × 10²³ molecules c) 1.32 × 10²⁴ electrons d) All of the above
Answer: d) All of the above
35) At STP, the density of CCl₄ vapour in g/L will be nearest to:
a) 6.87 b) 3.42 c) 10.26 d) 4.57
Answer: a) 6.87
36) The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is:
a) 20 b) 30 c) 40 d) 10
Answer: b) 30
37) 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (Atomic weight of Mg = 24):
a) 75 b) 96 c) 60 d) 84
Answer: d) 84
38) What is the mass of precipitate formed when 50 mL of 16.9% solution of AgNO₃ is mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5):
a) 28 g b) 3.5 g c) 7 g d) 14 g
Answer: c) 7 g
39) When 22.4 L of H₂(g) is mixed with 11.2 L of Cl₂(g), each at STP, the moles of HCl(g) formed is equal to:
a) 1 mole of HCl(g) b) 2 moles of HCl(g) c) 0.5 mole of HCl(g) d) 1.5 moles of HCl(g)
Answer: a) 1 mole of HCl(g)
40) 1.0 g of magnesium is burnt with 0.56 g of oxygen in a closed vessel. Which reactant is left in excess and how much?
a) Mg, 0.16 g b) O₂, 0.16 g c) Mg, 0.44 g d) O₂, 0.28 g
Answer: a) Mg, 0.16 g
41) 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be:
a) 2 moles b) 3 moles c) 4 moles d) 1 mole
Answer: c) 4 moles
42) How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl?
a) 0.044 b) 0.333 c) 0.011 d) 0.029
Answer: d) 0.029
43) What volume of oxygen gas (O₂) measured at 0°C and 1 atm, is needed to burn completely 1L of propane gas (C₃H₈) measured under the same conditions?
a) 7 L b) 6 L c) 5 L d) 10 L
Answer: c) 5 L
44) Number of moles of MnO₄⁻ required to oxidize one mole of ferrous oxalate completely in acidic medium will be:
a) 0.6 mole b) 0.4 mole c) 7.5 moles d) 0.2 mole
Answer: b) 0.4 mole
45) The number of moles of KMnO₄ that will be needed to react with one mole of sulphite ion in acidic solution is:
a) 4/5 b) 2/5 c) 1 d) 3/5
Answer: b) 2/5

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