s Block Elements

CHEMISTRY CHAPTER : s-Block Elements Objective Questions I [Only one correct option] 1.

The temporary hardness of water is due to calcium bicarbonate can be removed by adding (1979, 1M)

a) CaCO3 2.

3.

4.

b) Ca(OH)2

c) CaCl2

Calcium is obtained by a) electrolysis of molten CaCl2 b) electrolysis of solution of CaCl2 in water c) reduction of CaCl2 with carbon d) roasting of limestone

(1996, 1M)

14.

A dilute aqueous solution of Na2SO4 is electrolysed using platinum electrodes. The products at the anode and cathode are respectively (1996, 1M) a) O2, H2 b) S2O82–, Na c) O2, Na d) S2O82–, H2

15.

A sodium salt of an unknown anion when treated with MgCl2 gives white precipitate only on boiling. The anion is (2004, 1M)

(1983, 1M)

a) SO42–

(1985,

1.

(1985, 1M)

b) Na2O2

c) MnO2

d) TiO2

7.

Nitrogen dioxide cannot be obtained by heating (1985, 1M) a) KNO3 b) Pb(NO3)2 c) Cu(NO3)2 d) AgNO3

8.

A solution of sodium sulphate in water is electrolysed using inert electrodes. The products at cathode and anode are respectively (1987, 1M) a) H2, O2 b) O2, H2 c) O2, Na d) O2, SO2 The metallic lustre exhibited by sodium metal is explained

9.

2.

(1987, 1M)

10.

11.

12.

The oxidation state of the most electronegative element in the products of the reaction, BaO2 with dil. H2SO4 are (1991, 1M) a) 0 and – 1 b) – 1 and – 2 c) – 2 and 0 d) – 2 and – 1 The species that do not contain peroxide ions, is (1992, 1M) a) PbO2 b) H2O2 c) SrO2 d) BaO2 Hydrolysis of one mole of peroxodisulphuric acid produces a) two moles of sulphuric acid (1996, 1M) b) two moles of peroxomono sulphuric acid c) one mole of sulphuric acid and one mole of peroxomono sulphuric acid

When zeolite, which is hydrated sodium aluminium silicate, is treated with hard water, the sodium ions are exchanged with (1990, 1M)

a) H+ ions d) Mg2+ ions 3.

by a) diffusion of sodium ions b) oscillation of loose electron c) excitation of free protons d) existence of body centred cubic lattice

Sodium sulphate is soluble in water, whereas barium sulphate is sparingly soluble because (1989, a) the hydration energy of sodium sulphate is more than its lattice energy b) the lattice energy of barium sulphate is more than its hydration energy c) the lattice energy has no role to play in solubility d) the hydration energy of sodium sulphate is less than its lattice energy

is a) PbO2

c) CO32– d) NO3–

1M)

b) CuSO4 . 5H2O d) Na2SO4 . 10H2O

The oxide that gives H2O2 on treatment with a dilute acid

6.

b) HCO3–

Objective Questions II [One or more than one correct option]

1M)

a) MgSO4 . 7H2O c) FeSO4 . 7H2O

The following compounds have been arranged in order of their increasing thermal stabilities. Identify the correct order. K2CO3 (I), MgCO3(II), CaCO3 (III), BeCO3(IV) a) I < II < III < IV b) IV < II < III < I c) IV < II < I < III d) II < IV < III < I

(1980, 1M)

Molecular formula of Glauber’s salt is

5.

13.

d) HCl

A solution of sodium metal in liquid ammonia is strongly reducing due to the presence of (1981, 1M) a) sodium atoms b) sodium hydride c) sodium amide d) solvated electrons Heavy water is a) H2O18 b) water obtained by repeated distillation c) D2O d) water at 4oC

d) one mole of sulphuric acid, one mole of peroxomono sulphuric acid and one mole of hydrogen peroxide

b) Ca2+ ions e) OH– ions

c) SO42– ions

The material used in solar cells contains a) Cs b) Si c) Sn

(1993, 1M)

d) Ti

Highly pure dilute solution of sodium in liquid ammonia

4.

(1998, 1M)

a) shows blue colour b) exhibits electrical conductivity c) produces sodium amide d) produces hydrogen gas Sodium nitrate decomposes above = 800oC to give

5.

(1998,

1M)

a) N2 6.

b) O2

c) NO2

d) Na2O

MgSO4 on reaction with NH4OH and Na2HPO4 forms a white crystalline precipitate. What is its formula? (2006, 1M)

a) Mg(NH4)PO4 c) MgCl2 . MgSO4

b) Mg3(PO4)3 d) MgSO4

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7.

The compound(s) formed upon combustion of sodium metal in excess air is (are) (2007,

1.

Water is a liquid, while H 2S is a gas at ordinary temperature. Explain. (1978)

2.

Sodium carbonate is prepared by Solvay process but the same process is not extended to the manufacture of potassium carbonate, explain. (1981)

3.

Give reason in one or two sentences for the following “H2O2 is a better oxidizing agent than H2O.”(1986)

4.

Arrange the following in increasing order of basic strength : MgO, SrO, K2O, NiO, Cs2O (1991)

5.

Complete and balance the following chemical reaction Anhydrous potassium nitrate is heated with excess of metallic potassium (1992) KNO3(s) + K(s)  … + …

6.

Calcium burns in nitrogen to produce a white powder which dissolves in sufficient water to produce a gas A and an alkaline solution. The solution on exposure to air produces a thin solid layer of B on the surface. Identify the compounds A and B. (1996)

7.

Element A burns in nitrogen to given an ionic compound B. Compound B reacts with water to give C and D. A solution of C becomes ‘milky’ on bubbling carbon dioxide gas. Identify A, B, C and D. (1997)

8.

The crystalline salts of alkaline earth metals contain more water of crystallization than the corresponding alkali metal salts. Why?(1997)

9.

Hydrogen peroxide acts both as an oxidizing and as a reducing agent in alkaline solution towards certain first row transition metal ions. Illustrate both these properties of H 2O2 using chemical equation. (1998)

10.

A white solid is ether Na2O or Na2O2. A piece of red litmus paper turns white when it is dipped into a freshly made aqueous solution of the white solid.(1999) i. Identify the substance and explain with balanced equation. ii. Explain what would happen to the red litmus if the white solid were the other compound.

11.

Give reasons for the following in one or two sentences only “BeCl2 can be easily hydrolysed.” (1999)

12.

Identify (X)in the following synthetic scheme and write their structures. (2001)

1M)

a) Na2O2 8.

b) Na2O

c) NaO2

d) NaOH

The reagent(s) used for softening the temporary hardness of water is(are) (2010, 1M) a) Ca3(PO4)2 b) Ca(OH)2 c) Na2CO3 d) NaOCl

Assertion and Reason Read the following questions and answer as per the direction given below: a. Statement – 1 is true, Statement – 2 is true and Statement – 2 is the correct explanation for statement – 1. b. Statement – 1 is true, Statement –2 is true but Statement – 2 is not the correct explanation for statement – 1. c. Statement – 1 is true, Statement – 2 is false. d. Statement – 1 is false, Statement – 2 is true. 1.

Statement I : The alkali metal can form ionic hydrides which contain the hydride ion, H–. Statement II : The alkali metals have low electro negativity, their hydrides conduct electricity when fused and liberate hydrogen gas at the anode. (1994, 1M)

2.

Statement I : LiCl is predominantly a covalent compound. Statement II : Electronegativity difference between Li and Cl is too small. (1998, 1M)

3.

Statement I : Alkali metals dissolve in liquid ammonia to give blue solutions. Statement II : Alkali metal in liquid ammonia give solvated species of the type [M(NH3)n] + (M = alkali metals). (2007, 1M)

Fill in the Blanks 1.

Iodine reacts with hot NaOH solution. The products are NaI and ………… (1980, 1M)

2.

Anhydrous MgCl2 is obtained by heating the hydrated salt with …………(1980)

3.

The adsorption of hydrogen by palladium is commonly known as …………(1983)

4.

Sodium dissolved in liquid ammonia conducts electricity because of …………(1985)

5.

Hydrogen gas is liberated by the action of aluminium with concentrated solution of…………(1987)

True / False 1. 2.



Ba C O3 + H2SO4  X (gas) (C* denotes C14)

MgCl2 . 6H2O on heating gives anhydrous MgCl2. (1982) Sodium when burnt in excess of oxygen gives sodium oxide. (1987)

Subjective Questions Page : 2