Chemistry Class-11: Chapter –10. The s-Block Elements Part – 7

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VI. Long Answer Type

Question: 46

The s-block elements are characterized by their larger atomic sizes, lower ionization enthalpies, invariable oxidation state and solubility of their oxosalts. In the light of these features describe the nature of their oxides, halides and oxosalts.

Answer:

Question: 47

Present a comparative account of the alkali and alkaline earth metals with respect to the following characteristics:

(i) Tendency to form ionic / covalent compounds

(ii) Nature of oxides and their solubility in water

(iii) Formation of oxosalts

(iv) Solubility of oxosalts

(v) Thermal stability of oxosalts

Answer:

Question: 48

When a metal of group 1 was dissolved in liquid ammonia, the following observations were obtained:

(i) Blue solution was obtained initially.

(ii) On concentrating the solution, blue colour changed to bronze colour. How do your account for the blue colour of the solution? Give the name of the product formed on keeping the solution for some time.

Answer:

Question: 49

The stability of peroxide and superoxide of alkali metals increase as we go down the group. Explain giving reason.

Answer:

Question: 50

When water is added to compound (A) of calcium, solution of compound (B) is formed. When carbon dioxide is passed into the solution, it turns milky due to the formation of compound (C). If excess of carbon dioxide is passed into the solution milkiness disappears due to the formation of compound (D). Identify the compounds A, B, C and D. Explain why the milkiness disappears in the last step.

Answer:

Compound: is soluble in water. Hence, milkiness of solution disappears on passing excess carbon dioxide into the solution of compound B.

Question: 51

Lithium hydride can be used to prepare other useful hydrides. Beryllium hydride is one of them. Suggest a route for the preparation of beryllium hydride starting from lithium hydride. Write chemical equations involved in the process

Answer:

Question: 52

An element of group 2 forms covalent oxide which is amphoteric in nature and dissolves in water to give an amphoteric hydroxide. Identify the element and write chemical reactions of the hydroxide of the element with an alkali and an acid.

Answer:

The element is beryllium

Question: 53

Ions of an element of group 1 participate in the transmission of nerve signals and transport of sugars and amino acids into cells. This element imparts yellow colour to the flame in flame test and forms an oxide and peroxide with oxygen. Identify the element and write chemical reaction to show the formation of its peroxide. Why does the element impart colour to the flame?

Answer:

The element is sodium.

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