Chapter 1: Basic Concepts of Chemistry and Chemical Calculations

40 ml of methane is completely burnt using 80 ml of oxygen at room temperature. The volume of gas left after cooling to room temperature
(a) 40 ml CO₂
(b) 40 ml CO₂ gas and 80 ml H₂o gas
(c) 60 ml CO₂ gas and 60 ml H₂o gas
(d) 120 ml CO₂ gas

(a) 40 ml CO₂

An element X has the following isotopic composition ²⁰⁰X = 90%, ¹⁹⁹X = 8% and ²⁰²X = 2%. The weighted average atomic mass of the element X is closest to
(a) 201 u
(b) 202 u
(c) 199 u
(d) 200 u

(d) 200 u

Assertion:
Two mole of glucose contains 12.044 × 10²³ molecules of glucose
Reason:
Total number of entities present in one mole of any substance is equal to 6.02 × 10²²
(a) both assertion and reason are true and the reason is the correct explanation of assertion
(b) both assertion and reason are true but reason is not the correct explanation of assertion
(c) assertion is true but reason is false
(d) both assertion and reason are false

(c) assertion is true but reason is false

Carbon forms two oxides, namely carbon monoxide and carbon dioxide. The equivalent mass of which element remains constant?
(a) Carbon
(b) Oxygen
(c) both carbon and oxygen
(d) neither carbon nor oxygen

(b) Oxygen

The equivalent mass of a trivalent metal element is 9 g eq^-1 the molar mass of its anhydrous oxide is
(a) 102 g
(b) 27 g
(c) 270 g
(d) 78 g

(a) 102 g

The number of water molecules in a drop of water weighing 0.018 g is
(a) 6.022 × 10²⁶
(b) 6.022 × 10²³
(c) 6.022 × 10²⁰
(d) 9.9 × 10²²

(c) 6.022 × 10²⁰

1 g of an impure sample of magnesium carbonate (containing no thermally decomposable impurities) on complete thermal decomposition gave 0.44 g of carbon dioxide gas. The percentage of impurity in the sample is
(a) 0 %
(b) 4.4 %
(c) 16 %
(d) 8.4 %

(c) 16 %

When 6.3 g of sodium bicarbonate is added to 30 g of acetic acid solution, the residual solution is found to weigh 33 g. The number of moles of carbon dioxide released in the reaction is
(a) 3
(b) 0.75
(c) 0.075
(d) 0.3

(c) 0.075

When 22.4 litres of H₂ (g) is mixed with 11.2 litres of Cl₂ (g), each at 273 K at 1 atm the moles of HCl (g), formed is equal to
(a) 2 moles of HCl (g)
(b) 0.5 moles of HCl (g)
(c) 1.5 moles of HCl (g)
(d) 1 moles of HCl (g)

(d) 1 moles of HCl (g)

Hot concentrated sulphuric acid is a moderately strong oxidising agent. Which of the following reactions does not show oxidising behaviour?
(a) Cu + 2H₂ → CuSO₄ + SO₂ +2 H₂O
(b) C + 2 H₂SO₄ → CO₂ + 2 SO₂ +2 H₂O
(c) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
(d) none of the above

(c) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl

Choose the disproportionation reaction among the following redox reactions.
(a) 3Mg_(s) + N_2(g) → Mg₃N_2(s)
(b) P_4(s) + 3NaOH + 3H₂O → PH_3(g) + 3NaH₂PO_2(aq)
(c) Cl_2(g) + 2KI_(aq) → 2KCl_(aq) + I_2(s)
(d) Cr₂O_3(s) + 2Al_(s) → Al₂O_3(s) + 2Cr_(s)

b) P_4(s) + 3NaOH + 3H₂O → PH_3(g) + 3NaH₂PO_2(aq)

The equivalent mass of potassium permanganate in an alkaline medium is
MnO₄ + 2H₂O + 3e → MnO₂ + 4OH^–
(a) 31.6
(b) 52.7
(c) 79
(d) None of these

(b) 52.7

Which one of the following represents 180g of water?
(a) 5 Moles of water
(b) 90 moles of water
(c) 6.022×10²³ / 180 molecules of water

(d) 6.022 × 10²⁴ water molecules

(d) 6.022 × 10²⁴ water molecules

7.5 g of a gas occupies a volume of 5.6 litres at 0° C and 1 atm pressure. The gas is
(a) NO
(b ) N₂O
(c) CO
(d) CO₂

(a) NO

Total number of electrons present in 1.7 g of ammonia is
(a) 6.022 × 10²³
(b) 6.022×1022 / 1.7
(c) 6.022×1024 / 1.7
(d) 6.022×1023 / 1.7

(a) 6.022 × 10²³

The correct increasing order of the oxidation state of sulphur in the anions
SO₄^2-, SO₃^2-, S₂O₄^2-, S₂O₆^2- is

(a) SO₃^2- < SO₄^2- < S₂O₄^2- < S₂O₆^2-

(b) SO₄^2- < S₂O₄^2- < S₂O₆^2- < SO₃^2-

(c) S₂O₄^2- < SO₃^2- < S₂O₆^2- < SO₄^2-

(d) S₂O₆^2- < S₂O₄^2- < SO₄^2- < SO₃^2-

(c) S₂O₄^2- < SO₃^2- < S₂O₆^2- < SO₄^2-

The equivalent mass of ferrous oxalate is
(a)  molar mass of ferrous oxalate / 1

(b)  molar mass of ferrous oxalate / 2

(c)  molar mass of ferrous oxalate / 3
(d) none of these

(c)  molar mass of ferrous oxalate / 3

If Avogadro number were changed from 6.022 × 10²³ to 6.022 × 10²⁰, this would change
(a) the ratio of chemical species to each other in a balanced equation
(b) the ratio of elements to each other in a compound
(c) the definition of mass in units of grams
(d) the mass of one mole of carbon

(d) the mass of one mole of carbon

Two 22.4 liter containers A and B contains 8 g of O₂ and 8 g of SO₂ respectively at 273 K and 1 atm pressure, then
(a) Number of molecules in A and B are the same
(b) Number of molecules in B is more than that in A.
(c) The ratio between the number of molecules in A to number of molecules in B is 2 : 1
(d) Number of molecules in B is three times greater than the number of molecules in A.

(c) The ratio between the number of molecules in A to number of molecules in B is 2 : 1

What is the mass of precipitate formed when 50 ml of 8.5 % solution of AgNO₃ is mixed with 100 ml of 1.865 % potassium chloride solution?
(a) 3.59 g
(b) 7 g
(c) 14 g
(d) 28 g

(a) 3.59 g

The mass of a gas that occupies a volume of 612.5 ml at room temperature and pressure (25°C and 1 atm pressure) is 1.1 g. The molar mass of the gas is
(a) 66.25 g mol^-1
(b) 44 g mol^-1
(c) 24.5 g mol^-1
(d) 662.5 g mol^-1

(b) 44 g mol^-1

Which of the following contain the same number of carbon atoms as in 6 g of carbon -12.
(a) 7.5 g ethane
(b) 8 g methane
(c) both (a) and (b)
(d) none of these

(c) both (a) and (b)

Which of the following compound(s) has/have a percentage of carbon same as that in ethylene (C₂H₄)
(a) Propene
(b) ethyne
(c) benzene
(d) ethane

(a) Propene

Which of the following is/are true with respect to carbon -12.
(a) relative atomic mass is 12 u
(b) oxidation number of carbon is +4 in all its compounds.
(c) 1 mole of carbon-12 contains 6.022 × 10²² carbon atoms.
(d) all of these

(a) relative atomic mass is 12 u

Which one of the following is used as a standard for atomic mass.
(a) ₆C¹²
(b) ₇C¹²
(c) ₆C¹³
(d) ₆C¹⁴

(a) ₆C¹²