Some Basic Concepts of Chemistry

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An aqueous solution of 6.3 g of oxalic acid dihydrate is made up to 250 ml. The volume of 0.1 N NaOH required to completely neutralise 10 ml of this solution is

(a) 20 ml

(b) 40 ml

(d) 4 ml

During electrolysis of water the volume of O₂ liberated is 2.24 dm³. The volume of hydrogen liberated, under same conditions will be

(a) 2.24 dm³

(b) 1.12 dm³

(d) 0.56 dm³

For preparing 0.1 N solution of a compound from its impure sample of which the percentage purity is known, the weight of the substance required will be

(a) less than the theoretical weight

(b) more than the theoretical weight

(d) none of these

The simplest formula of a compound containing 50% of element X (atomic mass 10) and 50% of element Y (atomic mass 20) is

(a) XY

(b) XY₃

(d) X₂Y₃

The weight of NaCl decomposed by 4.9g of H₂SO₄, if 6 g of sodium hydrogen sulphate and 1.825 g of HCl, were produced in the reaction is:

(a) 6.921 g

(b) 4.65 g

(d) 1.4 g

3g of an oxide of a metal is converted to chloride completely and it yielded 5g of chloride. The equivalent weight of the metal is

(a) 3.325

(b) 33.25

(d) 20

Given the numbers: 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is

(a) 3, 4 and 5 respectively

(b) 3, 3 and 4 respectively

(d) 3, 4 and 4 respectively

The weight of a single atom of oxygen is:

(a) 1.057 × 10²³ g

(b) 3.556 × 10²³ g

(d) 4.538 × 10^–23 g

Which one of the following is the lightest?

(a) 0.2 mole of hydrogen gas

(b) 6.023 × 10²² molecules of nitrogen

(d) 0.1 mole of oxygen gas

The oxide of an element contains 67.67% oxygen and the vapour density of its volatile chloride is 79. Equivalent weight of the element is:

(a) 2.46

(b) 3.82

(d) 4.96

In a hydrocarbon, mass ratio of hydrogen and carbon is 1:3, the empirical formula of hydrocarbon is

(a) CH₄

(b) CH₂

(d) CH₃

Which has the maximum number of molecules among the following?

(a) 44 g CO₂

(b) 48 g O₃

(d) 64 g SO₂

Arrange the following in the order of increasing mass (atomic mass: O = 16, Cu = 63, N = 14)
I. one atom of oxygen
II. one atom of nitrogen
III. 1 × 10^–10 mole of oxygen
IV. 1 × 10^–10 mole of copper

(a) II < I < III < IV

(b) I < II < III < IV

(d) IV < II < III < I

KMnO₄ reacts with oxalic acid according to the equation:

2MnO₄^– + 5C₂O₄^– + 16H⁺ → 2Mn⁺⁺ + 10CO₂ + 8H₂O
Here 20 mL of 0.1 M KMnO₄ is equivalent to:

(a) 20 mL of 0.5 M H₂C₂O₄

(b) 50 mL of 0.5 M H₂C₂O₄

(d) 20 mL of 0.1 M H₂C₂O₄

Which of the following pairs of solutions are expected to be isotonic, temperature being the same?

(a) 0.1 M glucose and 0.1 M C₆H₅N⁺H₃Cl^–

(b) 0.1 M NaCl and 0.05 M BaCl₂

(d) 0.1 M BaCl₂ and 0.075 M FeCl₃

60 gm of an organic compound on analysis is found to have C = 24 g, H = 4 g and O = 32 g. The empirical formula of compound is:

(a) CH₂O

(b) CHO

(d) C₂H₂O₂

One of the following combination which illustrates the law of reciprocal proportions?

(a) N₂O₃,N₂O₄, N₂O₅

(b) NaCl, NaBr, NaI

(d) PH₃, P₂O₃, P₂O₅

0.4 moles of HCl and 0.2 moles of CaCl₂ were dissolved in water to have 500 mL of solution, the molarity of Cl^– ion is:

(a) 0.8 M

(b) 1.6 M

(d) 10.0 M

The number of moles of oxygen in one litre of air containing 21% oxygen by volume, tmder standard conditions are

(a) 0.0093 mole

(b) 0.21 mole

(d) 0.186 mole

Calculate the millimoles of SeO₃^2– in solution on the basis of following data:
70ml of M/60 solution of KBrO₃ was added to SeO₃^2– solution. The bromine evolved was removed by boiling and excess of KBrO₃ was back titrated with 12.5 mL of M/25 solution of NaAsO₂.
The reactions are given below.

I. SeO₃^2– + BrO₃^– + H⁺ → SeO₄^2– + Br₂ + H₂O
II. BrO₃^– + AsO₂^– + H₂O → Br^– + AsO₄^3– + H⁺

(a) 1.6 × 10^–3

(b) 1.25

(d) None of these

The set of numerical coefficients that balances the equation
K₂CrO₄ + HCl → K₂Cr₂O₇ + KCl + H₂O is

(a) 2, 2, 1, 2, 1

(b) 2, 2, 1, 1, 1

(d) 1, 1, 2, 2, 1

Calculate the normality of 10 volume H₂O₂?

(a) 1.7 N

(b) 12 N

(d) 0.0303

If the true value for an experimental result is 6.23 and the results reported by three students X, Y, Z are:
X: 6.18 and 6.28
Y: 6.20 and 6.023
Z: 6.22 and 6.24
Which of the following option is correct:

(a) X precise, Y accurate, Z precise and accurate

(b) X precise and accurate, Y not precise, Z precise

(d) Both X & Y neither precise nor accurate, Z both precise and accurate

A solution is prepared by dissolving 24.5 g of sodium hydroxide in distilled water to give 1 L solution. The molarity of NaOH in the solution is
(Given that molar mass of NaOH = 40.0 g mol^–1)

(a) 0.2450 M

(b) 0.6125 M

(d) 1.6326 M

The molarity of H₂SO₄ solution, which has a density 1.84 g/cc. at 35° C and contains 98% by weight, is:

(a) 1.84 M

(b) 18.4 M

(d) 24.5 M

Volume of a gas at NTP is 1.12 × 10^–7 cc. The number of molecule in it is:

(a) 3.01 × 10¹²

(b) 3.01 × 10¹⁸

(d) 3.01× 10³⁰

Match the cohunns

Column-I (Number)	Column-II (Significant figures)
A. 29900.	I. 2
B. 290	II. 1
C. 1.23 × 1.331	III. 4
D. 20.00	IV. 3
E. 2.783–1	V. 5

(a) A – III; B – II; C – V; D – I; E – IV

(b) A – V; B – I; C – IV; D – III; E – II

(d) A – V; B – IV; C – III; D – II; E – I

The weight of one molecule of a compound of molecular formula C₆₀H₁₂₂ is

(a) 1.2 × 10^–20 g

(b) 5.025 × 10²³ g

(d) 6.023 × 10^–20 g

The maximum number of molecules are present in

(a) 15 L of H₂ gas at STP

(b) 5 L of N₂ gas at STP

(d) 10 g of O₂ gas

The empirical formula of a compound is CH₂O. Its molecular weight is 180. The molecular formula of compound is:

(a) C₄HO₄

(b) C₃H₆O₃

(d) C₅H₁₀O₅

The normality of orthophosphoric acid having purity of 70% by weight and specific gravity 1.54 is:

(a) 11 N

(b) 22 N

(d) 44 N

Match the columns

Column-I	Column-II
A. 88g of CO₂	I. 0.25 mole
B. 6.022 × 10²³ molecules	II. 2 mole of H₂O
C. 5.6 litres of O2 at STP	III. 1 mole
D. 96g of O₂	IV. 6.022×10²³ molecules
E. 1 mol of any gas	V. 3 mole

(a) A-II; B-III; C-I; D-V; E-VI

(b) A-III; B-II; C-I; D-V; E-IV

(d) A-II; B-III; C-I; D-IV; E-V

The reaction of calcium with water is represented by the equation
Ca + 2H₂O → Ca(OH)₂ + H₂
What volume of H₂ at STP would be liberated when 8 gm of calcium completely reacts with water?

(a) 0.2 cm³

(b) 0.4 cm³

(d) 4480 cm³

The density of 3M solution of sodium chloride is 1.252 g mL^–1. The molality of the solution will be:
(molar mass, NaCl = 58.5 g mol^–1)

(a) 260m

(b) 2.18m

(d) 3.00m

Volume of water needed to mix with 10 mL 10N HNO₃ to get 0.1 N HNO₃ is:

(a) 1000 mL

(b) 990 mL

(d) 10 mL

Sulphur forms the chlorides S₂C_l2 and SCl₂. The equivalent mass of sulphur in SCl₂ is

(a) 8 g/mol

(b) 16 g/mol

(d) 32 g/mol

The number of atoms in 0.1 mole of a triatomic gas is:
(N_A = 6.02×10²³ mol^–1)

(a) 6.026 × 10²²

(b) 1.806 × 10²³

(d) 1.800 × 10²²

If N_A is Avogadro’s number then numberofvalenceelectrons in 4.2 g of nitride ions (N^3–) is

(a) 4.2N_A

(b) 2.4N_A

(d) 3.2N_A

10²¹ molecules are removed from 200 mg of CO₂. The moles of CO₂ left are :

(a) 2.88 × 10^–3

(b) 28.8 × 10^–3

(d) 28.8 × 10³

The normality of solution obtained by mixing (10ml of N/5 HCI) and (30 ml of N/10 HCl) is:

(a) N/15

(b) N/5

(d) N/8

Number of grams of oxygen in 32.2g Na₂SO₄.10H₂O is

(a) 20.8

(b) 2.24

(d) 2.08

The vapour density of a mixture containing NO₂ and N₂O₄ is 27.6. Mole fraction of NO₂ in the mixture is

(a) 0.8

(b) 0.6

(d) 0.2

Temperature does not affect:

(a) Molality

(b) Formality

(d) Normality

1 cc. N₂O at NTP contains:

(a) (1.8/224) × 10²² atoms

(b) (6.02/22400) × 10²³ molecules

(d) all the above

The molar concentration of 20 g of NaOH present in 5 litre of solution is:

(a) 0.1 moles/litre

(b) 0.2 moles/litre

(d) 2.0 moles/litre

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