Explore topic-wise InterviewSolutions in Current Affairs.

(a) Statements-I and II are correct and statement-II is the correct explanation of statement-I

Answer: (a) +1

(c) (ii) and (iii)

Answer: (a) LlCl

The loosely held “s” electron in the outermost shell of these elements make them as the most electropositive metals. They readily lose electron to give monovalent M ions. Hence they are never found in free state in nature.

Answer: (b) LiClO₄

(b) (ii) only

Answer: (c) high

• Potassium has a vital role in biological system. 
• Potassium chloride is used as a fertilizer. 
• Potassium hydroxide is used in the manufacture of soft soap. 
• Potassium hydroxide is also used as an excellent absorbent of carbon dioxide.

Sodium bicarbonate is called as baking soda. Because it decomposes on heating to generate bubbles of carbon dioxide, leaving holes in cakes or pastries and making them light and fluffy.

(a) NaHCO₃ is used as an ingredient in baking.

(b) It is used as a mild antiseptic for skin infections. 

(c) It is also used in fire extinguishers

• Sodium hydroxide is used as laboratory reagent. 
• It is used in the purification of bauxite and petroleum refining. 
• It is used in the textile industries for mercerising cotton fabrics. 
• It is used in the manufacture of soap, paper, artificial silk and a number of chemicals.

(a) Li⁺ has minimum degree of hydration among alkali metal cations. 

Li⁺ has maximum degree of hydration among alkali metal cations. 

Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺

(i). Group 2 elements except beryllium are commonly known as alkaline earth metals because their oxides and hydroxides are alkaline in nature and these metal oxides are found in the Earth’s crust. 

(ii). Many alkaline earth metals are used in creating colours and used in fireworks.

(iii). Their general electronic configuration is ns² . 

(iv). Atomic and ionic radii of alkaline earth metals are smaller than alkali metals, on moving down the group, the radii increases. 

(v). These elements exhibit +2 oxidation state in their compounds. 

(vi). Alkaline earth metals have higher ionizatoin enthalpy values than alkali metals and they are less electropositive than alkali metals. 

(vii). Hydration enthalpies of alkaline earth metals decreases as we go down the group. 

(viii). Electronegativity values of alkaline earth metals decrease down the group. 

(ix). Alkaline earth metal salts moistened with concentrated hydrochloric acid gave a characteristic coloured flame, when heated on a platinum wire in a flame.

Potassium reacts even more violently. The liberated hydrogen catches fire instantly and burns with a lilac coloured flame because of potassium. 

2K + 2H₂O → 2KOH + H₂↑ + heat

(a) Crude salt contains sodium sulphate, calcium sulphate, calcium chloride and magnesium chloride as impurities along with sodium chloride. 

(b) Pure NaCl is obtained from crude salt by removal of insoluble impurities through filtration from the crude salt solution with minimum amount of water. 

(c) Sodium chloride can be crystallized by passing HCl gas into this solution. 

(d) Calcium and magnesium chloride being more soluble than NaCl, remain in solution.

(c) kerosene

All the alkaline earth metals combine with halogen at elevated temperature to form their halides.

M + X₂ → MX₂ , Where M = Be, Mg,Ca,Sr,Ba and Ra. X= F,Cl,Br and I. 

For example, Be + Cl₂ → BeCl₂

Sodium reacts so rapidly with water with the evolution of heat. The metal whizzes around the surface of water. The hydrogen gas liberated may catch fire giving yellow-colored flame because of sodium. 

2Na + 2H₂O → 2NaOH + H₂↑ + heat

(a) Magnesium chloride

(c) A - 2, B - 3, C - 4, D - 1

(i). This reaction is an exothermic reaction. Sodium hydroxide being a strong base, completely dissociated in aqueous medium. The heat evolved increases the stability. This phenomenon is strong enough to prove that sodium hydroxide crystals are readily dissolved in water.

(ii). NaCl is geologically stable. If kept dry, it will remain a free flowing solid for years. Water can dissolve NaCl because the Na⁺ ions are attracted by OH^- in water and Cl^- ions are attracted by H⁺ in water. The solubility of NaCl does not increase the temperature. Based on this, NaOH is much more soluble due to exothermic nature than sodium chloride.

The decrease in ionization enthalpy down the group permits easy availability of electrons to forms H ions. So, the hydrides behave as reducing agent. Their reducing nature increases down the group.

Alkali metals combine readily with halogens to form ionic halides M⁺ X^- . Reactivity of alkali metals with halogen increases down the group because of corresponding increase in electropositive character. 

2M + X₂ → 2M⁺X^- (M = Li, Na, K, Rb and Cs) (X F, Cl, Br and I)

• In self-luminous paints for watches. 
• In nuclear panels. 
• In aircraft switches. 
• In clocks and instrument dials.

A substance which is in gaseous state at room temperature is called a gas. However, if a Substance is not in gaseous state at room temperature but changes into gaseous state on heating, then the gaseous state obtained is called vapour or when a gas is below its critical temperature, it is called vapour.

Beryllium ion (Be²⁺) is smaller in size and it is involved in equal sharing of electrons with halogens to form covalent bond, whereas magnesium ion (Mg²⁺) is bigger and it is involved in transfer of electrons to form ionic bond.

All alkali metals react with hydrogen at about 673K (lithium at 1073K) to form their hydrides, which are ionic in nature. Reactivity of alkali metals with hydrogen increases from Li to Cs. 

2M + H₂ → 2 M⁺H^- (where M = Li, Na, K, Rb and Cs)

(b) Correct explanation : O₂^- has higher negative charge than F^-.

• The fact that a small cation can stabilize a small anion and a large cation can stabilize a large anion explains the formation and stability of the oxides.
• The size of Li⁺ ion is very small and it has a strong positive field around it. It can combine with only small anion, O^2- ion, resulting in the formation of monoxide Li₂O.
• The Na ion is a larger cation and has a weak positive field around it and can stabilize a bigger peroxide ion, \(O_2^{2-}\) or [-O-O-]² resulting in the formation of peroxide Na₂O₂ .

Beryllium oxide (BeO) is covalent due to the small size of Be²⁺ ion, while magnesium oxide (MgO) is ionic due to the bigger size of Mg²⁺ ion.

Answer: (a) lithium

Answer: (c) Mg

(i) The electron gain enthalpy of O is positive while that of S is negative because of repulsions between the electrons on O^- and the additional incoming electron.

(ii) Electron gain enthalpy of O is more positive than that of S^- due to small size which causes repulsions between O^- and the incoming electron is much more than in S^-

(iii) The electron gain enthalpy of N is positive while that of P is negative because of repulsion between N^- and the incoming electron.

All the alkaline earth metals form carbonates (MCO₃). All these carbonates decompose on heating to give CO₂ and metal oxide. The thermal stability; of these carbonates increases down the group, i.e., from Be to Ba,
BeCO₃ < MgCO₃ < CaCO₃ < SrCO₃ < BaCO₃
BeCO₃ is unstable to the extent that it is stable only in atmosphere of CO₂. It however shows reversible decomposition in closed container 

BeCO₃ ⇌ BeO + CO₂

Hence, more is the stability of oxide formed, less will be stability of carbonates. Stability of oxides decreases down the group. Since beryllium oxide is high stable, it makes BeCO₃ unstable.

(a) Castners process Castner’s process

NaOH ⇌ Na⁺ + OH^- 

Cathode : Na⁺ + e^- → Na 

Anode : 2OH^- → H₂O + \(\frac{1}{2}\)O₂ + 2e^-

2- methylbut -3-en-2-ol.

2- Bromo-3- methylbut-2-en-1-ol.

3-Phenyl-prop-2- en-1-ol

2-Bromo-3-methylbut-2-en-1-ol.

2-Methyl-Propan-2-ol.

3-Bromo-3-methyl but-2-en-1-ol.

2- Phenylethanol.

John Macpherson, a captain in the British army, had written that letter, dated Dec. 26, 1914, to his wife Connie. one point. The countries should have better resolved their disputes by playing a football or cricket match because no one dies in a match whereas war leaves behind orphans and widows.

The game was finished, so did the drinks and cakes. Jim told Hans that they hoped to see families as soon as the fighting ended by Christmas next year. The author put the letter back into the envelope and drove into Bridport. He just wanted to hand over the letter to Connie (Mrs Macpherson). Connie was now 101 years old. Her house had caught fire, but she was saved. She was in the conservatory of a nursing home.

The author wished her ‘Happy Christmas’ and gave the letter to her. She recognised the writing of her husband and felt very happy. She mistook the author for Jim who had come home, as promised on Christmas. She kissed the author on the cheek and asked him to read the letter to her. She wanted to listen to the voice of her husband. She said that he (Jim) himself was the best Christmas present to her.

1. They celebrated Christmas with rum s ration and exchanging sausage.

2. They celebrated Christmas on ‘no man’s land’.

3. The characters of the novel ‘Far from l the Madding Crowd’ by Thomas Hardy was the topic of talks between Jim and Hans Wolf.

4. Jim shared the Christmas cake prepared by his wife Connie with Hans Wolf.

(1) I moved out of the parking lot carefully because it was adjacent to a very busy street.

(2) Drug abuse causes a great damage on the lives of people.

(3) We could have beaten them in last week’s game, but they just got control over us from the start.

(4) I thought the meeting ended up really well!

(5) When they reached mid-sea, their supplies got exhausted.

1. The narrator had to find out the whereabouts of Connie Macpherson and deliver the letter to her.

2. When the narrator reached the house no. 12, he found that it had turned out to be nothing but a burned-out shell, the roof gaping and the windows boarded up.

3. Here the word ‘muddle-headed’ in reference to Connie Macpherson indicates that she was not in a stable state of mind.

4. Connie Macpherson used candles in place of electricity as she thought that electricity was rather too expensive.

The author found Jim’s letter in a small black tin box, put in the drawer of an old table. Jim’s letter was addressed to his wife. He was a British soldier but he was glad to have celebrated Christmas together s with the German soldiers. He had narrated the whole event in the letter and promised to come back home before next Christmas.

1. False

2. False

3. True

4. True

5. True

6. True

A. Connie Macpherson