The s-Block Elements

Q 1.

Arrange the following in the increasing order of solubility in water.
 MgCl₂, CaCl₂, SrCl₂, BaCl₂

Q 2.

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

Q 3.

What is dead burnt plaster?

Q 4.

The order of decreasing ionization enthalpy in alkali metals is

(a) Na > Li > K > Rb (b) Rb < Na < K < Li

(c) Li > Na > K > Rb (d) K < Li < Na < Rb

Q 5.

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
(a) ionic nature of lithium fluoride. . .
(b) high lattice enthalpy. ‘
(c) high hydration enthalpy for lithium ion.
(d) low ionization enthalpy of lithium atom.

Q 6.

Why are alkali metals soft and have low melting points?

Q 7.

The reducing power of a metal depends oh various factors. Suggest the factor which makes Li, the strongest reducing agent in aqueous solution.
(a) Sublimation enthalpy (b) Ionisation enthalpy
(c) Hydration enthalpy (d) Electron-gain enthalpy

Q 8.

Suspension of slaked lime in water is known as
(a) lime water                                                                                    
(b) quick lime
(c) milk of lime                                                                              
(d) aqueous solution of slaked lime

Q 9.

Why does the solution of alkali metals becomes blue in liquid ammonia? Give the chemical equation also.

Q 10.

(a) Compare four properties of alkali metals and alkaline earth metals.
(b) What happens when alkali metals are dissolved in ammonia?
(c) MgCl₂ is electrolysed.

Q 11.

Which of the carbonates given below is unstable in air and is kept in C0₂ atmosphere to avoid decomposition.
(a) BeCO₃
(b) MgC0₃
(c) CaC0₃
(d) BaCO₃

Q 12.

Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals do so. Why?

Q 13.

The hydroxides and carbonates of sodium and potassium are easily soluble in water while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain.

Q 14.

Why are lithium salts commonly hydrated and those of the other alkali metal ions usually anhydrous?

Q 15.

Explain the significance of sodium, potassium, magnesium and calcium in biological fluids.

Q 16.

Write the chemical formula of the following compounds.
(i) Chile salt petre (ii) Marble (iii) Brine

Q 17.

Why are alkali metals not found in nature?

Q 18.

Compare the alkali metals and alkaline earth metals with respect to (i) ionization enthalpy, (ii) basicity of oxides, (iii) solubility of hydroxides.

Q 19.

When alkali metal dissolves in liquid ammonia, the solution can acquire different colours. Explain the reason for this type of colour change.

Q 20.

Name the alkali metal which shows diagonal relationship with magnesium?

Q 21.

Name the alkaline earth metals whose salt do not impart colour to a non-luminous flame.

Q 22.

Which of the following statements is true about Ca(OH)₂?
(a) It is used in the preparation of bleaching powder.
(b) It is a light blue solid.
(c) It does not possess disinfectant property.
(d) It is used in the manufacture of cement.

Q 23.

Give the chemical formula of Epsom salt.

Q 24.

What is the mixture of CaC₂ and N₂ called? How is it prepared?

Q 25.

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

Q 26.

Describe two important uses of each of the following: ,
(i) caustic soda (ii) sodium carbonate (iii) quick lime

Q 27.

What happens when
(i) Sodium metal is dropped in water?
(ii) Sodium metal is heated in free supply of air?
(iii) Sodium peroxide dissolves in water?

Q 28.

(a) What makes lithium to show properties uncommon to the rest of the alkali metals?
(b) When is a cation highly polarising? Which alkali metal cation has the highest polarising power?

Q 29.

Which out of the following can be used to store an alkali metal?
H₂O, C₂H₅OH and Benzene

Q 30.

Metal carbonates decompose on heating to give metal oxide and carbon dioxide. Which of the metal carbonates is most stable thermally?
(a) MgC0₃
(b)CaC0₃
(c)SrCQ₃                              
(d)BaC0₃

Q 31.

Explain why can alkali and alkaline earth metals not be obtained by chemical reduction method.

Q 32.

Potassium carbonate cannot be prepared by Solvay process. Why?

Q 33.

What is the general name for elements of group 1 ?

Q 34.

Metallic elements are described by their standard electrode potential, frision enthalpy, atomic size, etc. The alkali metals are characterized by which of the following properties?
(a) High boiling point. ‘
(b) High negative standard electrode potential.
(c) High density.
(d) Large atomic size.

Q 35.

Explain why is sodium less reactive than potassium.

Q 36.

What happens when (i) magnesium is burnt in air, (ii) Quick lime is heated with silica (iii) chlorine reacts with slaked lime (iv) calcium nitrate is heated?

Q 37.

Write balanced equations for reactions between.
(a) Na₂O₂ and water
(b) KO₂ and water
(c) Na₂O and CO₂

Q 38.

Why are alkali metals always univalent? Which alkali metal ion forms largest hydrated ion in aqueous solution?

Q 39.

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

Q 40.

Which one of the following alkaline earth metal carbonates is thermally most stable?
(a) MgCO₃ (b) CaCO₃ (c) SrCO₃ (d) BaCO₃

Q 41.

What is Quick lime? What happens when it is added to water?

Q 42.

How would you prepare sodium silicate from silica?

Q 43.

Why are alkali metals soft?

Q 44.

Which is more basic NaOH or Mg(OH)₂?

Q 45.

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

Q 46.

In the Solvay process, can we obtain sodium carbonate directly by treating the solution containing (NH₄)₂C0₃ with sodium chloride? Explain.

Q 47.

In what ways lithium shows similarities to magnesium in its chemical behaviour?

Q 48.

Why are potassium and caesium, rather than lithium used in photoelectric cells?

Q 49.

Why is Li₂CO₃ decomposed at a lower temperature whereas Na₂CO₃ at higher temperature?

Q 50.

Give the important uses of the following compounds.
(i) NaHCO₃ (ii) NaOH