The S-block Elements

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Correct option (i) and (iii)

Na₂CO₃ is used in paper paints and textile industry. It is used to manufacture soap powders.

NaOH is used in textile industry for mercerising cotton fabrics.

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Correct option (ii) and (iv)

Alkali metals have larger atomic size and low density. These metals lose electrons due to less effective nuclear charge. They have a high value of electrode potential.

Lithium has the highest negative reduction potential value. Due to the small size of lithium it has a small atomic size and  the highest ionization enthalpy.

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Correct option (iv)

Chlorides of alkaline earth metals are hydrated salts. They can be used as dehydrating agents due to their hygroscopic nature to absorb moisture from air. Extent of hydration decreases from Mg to Ba.

Therefore, dehydration of hydrates of halides of calcium, barium and strontium i.e., CaCl₂.6H₂O, BaCl₂.2H₂O, SrCl₂.2H₂O can be achieved by heating.

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Correct Option (iii)

The chemical formula of A is Ca (OH)₂ Sodium carbonate is prepared by Solvay's process. In this process, ammonia is recovered when ammonium chloride reacts with calcium hydroxide. On reacting NH₄Cl with Ca (OH)₂, calcium chloride is obtained as a by-product. The reaction is given below.

2NH₄Cl+Ca (OH)₂→2NH₃+CaCl₂+H₂O

When CO₂ is bubbled through an aqueous solution of Ca (OH)₂ the solution turns milky. It is used in whitewashing due to its disinfectant nature.

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Correct option (i)

Calcium hydroxide is used in the preparation of bleaching powder. It reacts with chlorine to form hypochlorite, a constituent of bleaching powder.

Ca (OH)₂+Cl₂→CaCl₂+H₂O+Ca (OCl)₂

It is a white amorphous powder and is sparingly soluble in water.

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Correct option (ii)

Alkali and alkaline metals impart characteristic color. Calcium gives brick red color, Strontium gives crimson red color, Barium gives apple green color, and radium gives crimson color. So, the compound is calcium nitrate. On heating calcium nitrate, it gives calcium oxide, nitrogen and nitrogen dioxide gas which is brown in color.

Ca (NO₃)²→CaO+O₂+NO₂↑

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Correct option (iv)

Anhydrous sodium carbonate is known as soda ash. The formula of soda ash is Na₂CO₃? It is also known as washing soda.

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Correct option (i)

Beryllium being least reactive does not form hydride by direct heating with dihydrogen. Also due to its small size and high ionization enthalpy it cannot form hydrides by direct heating.

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Correct Option (iii)

Ca (OH)₂ saked lime is only sparingly soluble in water. When CaO is soaked in water, it produces a white suspension, and the reaction is highly exothermic. White suspension is called milk of lime and it is used for white washing.

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Correct option (i)

An anhydrous calcium sulfate is dead burnt paris. It is known as dead burnt because it does not set like plaster when moistened with water. When gypsum is heated the water of crystallization is lost and an anhydrous calcium sulphate is obtained.