Solution of Chapter 10. The s -block Elements (Chemistry - Exemplar Book)

The alkali metals are low melting. Which of the following alkali metal is expected to melt if the room temperature rises to 30°C?

Alkali metals react with water vigorously to form hydroxides and dihydrogen. Which of the following alkali metals reacts with water least vigorously?

The reducing power of a metal depends on various factors. Suggest the factor which makes Li, the strongest reducing agent in aqueous solution.

Metal carbonates decompose on heating to give metal oxide and carbon dioxide. Which of the metal carbonates is most stable thermally?

Which of the carbonates given below is unstable in air and is kept in CO₂ atmosphere to avoid decomposition.

Metals form basic hydroxides. Which of the following metal hydroxide is the least basic?

Some of the Group 2 metal halides are covalent and soluble in organic solvents. Among the following metal halides, the one which is soluble in ethanol is

The order of decreasing ionisation enthalpy in alkali metals is

The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to

Amphoteric hydroxides react with both alkalies and acids. Which of the following Group 2 metal hydroxides is soluble in sodium hydroxide?

In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH₄Cl with Ca(OH)₂. The by-product obtained in this process is

When sodium is dissolved in liquid ammonia, a solution of deep blue colour is obtained. The colour of the solution is due to

By adding gypsum to cement

Dead burnt plaster is

Suspension of slaked lime in water is known as

Which of the following elements does not form hydride by direct heating with dihydrogen?

The formula of soda ash is

A substance which gives brick red flame and breaks down on heating to give oxygen and a brown gas is

Which of the following statements is true about Ca(OH)₂?

A chemical A is used for the preparation of washing soda to recover ammonia. When CO₂ is bubbled through an aqueous solution of A, the solution turns milky. It is used in white washing due to disinfectant nature. What is the chemical formula of A?

Dehydration of hydrates of halides of calcium, barium and strontium i.e., CaCl₂6H₂O, BaCl₂ .2H₂ O, SrCl₂.2H₂O, can be achieved by heating. These become wet on keeping in air. Which of the following statements is correct about these halides?

In the following question two or more options may be correct.

Metallic elements are described by their standard electrode potential, fusion enthalpy, atomic size, etc. The alkali metals are characterised by which of the following properties?

In the following question two or more options may be correct.

Several sodium compounds find use in industries. Which of the following compounds are used for textile industry?

In the following question two or more options may be correct.

Which of the following compounds are readily soluble in water?

In the following question two or more options may be correct.

When Zeolite, which is hydrated sodium aluminium silicate is treated with hard water, the sodium ions are exchanged with which of the following ion(s)?

In the following question two or more options may be correct.

Identify the correct formula of halides of alkaline earth metals from the following.

In the following question two or more options may be correct.

Choose the correct statements from the following.

In the following question two or more options may be correct.

Which of the following are the correct reasons for anomalous behaviour of lithium?

How do you account for the strong reducing power of lithium in aqueous solution?

When heated in air, the alkali metals form various oxides. Mention the oxides formed by Li, Na and K.

Complete the following reactions

(i) O^2-₂ + H₂O →

(ii) O^-₂ + H₂O →

Lithium resembles magnesium in some of its properties. Mention two such properties and give reasons for this resemblance.

Name an element from Group 2 which forms an amphoteric oxide and a water soluble sulphate.

Discuss the trend of the following:

(i) Thermal stability of carbonates of Group 2 elements.

(ii) The solubility and the nature of oxides of Group 2 elements.

Why are BeSO₄ and MgSO₄ readily soluble in water while CaSO₄, SrSO₄ and BaSO₄ are insoluble?

All compounds of alkali metals are easily soluble in water but lithium compounds are more soluble in organic solvents. Explain.

In the Solvay process, can we obtain sodium carbonate directly by treating the solution containing (NH₄) 2CO₃ with sodium chloride? Explain.

Write Lewis strucure of O^-₂ ion and find out oxidation state of each oxygen atom? What is the average oxidation state of oxygen in this ion?

Why do beryllium and magnesium not impart colour to the flame in the flame test?

What is the structure of BeCl₂ molecule in gaseous and solid state?

Match the elements given in Column I with the properties mentioned in Column II.

Match the compounds given in Column I with their uses mentioned in Column II.

Match the elements given in Column I with the colour they impart to the flame given in Column II.

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): The carbonate of lithium decomposes easily on heating to form lithium oxide and CO₂.

Reason (R) : Lithium being very small in size polarises large carbonate ion leading to the formation of more stable Li₂O and CO₂ .

(i) Both A and R are correct and R is the correct explanation of A.

(ii) Both A and R are correct but R is not the correct explanation of A.

(iii) Both A and R are not correct

(iv) A is not correct but R is correct.

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): Beryllium carbonate is kept in the atmosphere of carbon dioxide.

Reason (R) : Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide.

(i) Both A and R are correct and R is the correct explanation of A.

(ii) Both A and R are correct but R is not the correct explanation of A.

(iii) Both A and R are not correct.

(iv) A is not correct but R is correct.

The s-block elements are characterised by their larger atomic sizes, lower ionisation enthalpies, invariable +1 oxidation state and solubilities of their oxosalts. In the light of these features describe the nature of their oxides, halides and oxosalts.

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

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 you account for the blue colour of the solution? Give the name of the product formed on keeping the solution for some time.

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

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.

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.

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.

Ions of an element of group 1 participate in the transmission of nerve signals and transport of sugars and aminoacids into cells. This element imparts yellow colour to the flame in flame test and forms an oxide and a 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?