All compounds of alkali metals are easily soluble in water but lithium compounds are more soluble in organic solvents. Explain.
Because of the small size, high electronegativity and high ionization enthalpy, lithium compounds have considerable covalent character while compounds of other alkali metals are ionic in nature. As a result, compounds of lithium are more soluble in organic solvents while those of other alkali metals are more soluble in water.
Lithium resembles magnesium in some of its properties. Mention two such properties and give reasons for this resemblance.
The alkali metals are low melting. Which of the following alkali metals is expected to melt if the room temperature rises to 30 °C?
(a) Na (b) K (c) Rb (d) Cs
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 does the solution of alkali metals becomes blue in liquid ammonia? Give the chemical equation also.
Match the elements given in Column I with the properties mentioned in Column II.
| Column I | Column II |
| (i) Li | (a) Insoluble sulphate |
| (ii) Na | (b) Strongest monoacidic base |
| (iii) Ca | (c) Most negative E ° value among alkali metals |
| (iv) Ba | (d) Insoluble oxalate ‘ |
| (e) 6s2 outer electronic configuration |
Identify the correct’ formula of halides of alkaline earth metals from the following.
(a) BaCl2.2H20
(b) BaCl2 .4H20
(c) CaCl2 . 6H20
(d) SrCl2.4H20
Match the elements given in Column I with the colour they impart to the flame given in Column II.
| Column I | Column II |
| (i) Cs | (a) Apple green |
| (ii) Na | (b) Violet |
| (iii) K | (c) Brick red |
| (iv) Ca | (d) Yellow |
| (v) Sr | (e) Crimson red |
| (vi) Ba | (f) Blue |
Arrange the following in the increasing order of solubility in water.
MgCl2, CaCl2, SrCl2, BaCl2
(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?
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
Which of the following are the correct reasons for anomalous behaviour of lithium?
(a) Exceptionally small size of its atom.
(b) Its high polarizing power.
(c) It has high degree of hydration.
(d) Exceptionally low ionization enthalpy.
Why are BeS04 and MgS04 readily soluble in water while CaS04, SrS04 and BaS04 are insoluble?
Explain why can alkali and alkaline earth metals not be obtained by chemical reduction method.
Why is LiF almost insoluble in water whereas LiCl soluble not only in water but also in acetone?
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
Why are alkali metals always univalent? Which alkali metal ion forms largest hydrated ion in aqueous solution?
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.
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.
Several sodium compounds find use in industries. Which of the following compounds are used for textile industry?
(a) Na2C03
(b) NaHC03
(c) NaOH
(d) NaCl
Choose the correct statements from the folio-wing.
(a) Beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal.
(b) Beryllium sulphate is readily soluble in water as the greater hydration enthalpy of Be2+ overcomes the lattice enthalpy factor.
(c) Beryllium exhibits coordination number more than four.
(d) Beryllium oxide is purely acidic in nature.
When alkali metal dissolves in liquid ammonia, the solution can acquire different colours. Explain the reason for this type of colour change.
Write balanced equations for reactions between.
(a) Na2O2 and water
(b) KO2 and water
(c) Na2O and CO2
Which one of the following alkali metals give hydrated salts?
(a) Li (b) Na (c) K (d) Cs
Which one of the following alkaline earth metal carbonates is thermally most stable?
(a) MgCO3 (b) CaCO3 (c) SrCO3 (d) BaCO3
Write the chemical formula of the following compounds.
(i) Chile salt petre (ii) Marble (iii) Brine
Why are ionic hydrides of only alkali metals and alkaline earth metals are known? Give two examples.
Amphoteric hydroxides react with both alkalies and acids. ‘Which of the following group 2 metal hydroxides is soluble in sodium hydroxide?
(a) Be(OH)2
(b) Mg(OH)2
(c) Ca(OH)2
(d) Ba(OH)2
In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH4C1 with Ca(OH)2. The by-product obtained in this process is
(a) CaCl2
(b) NaCl
(c) NaOH
(d) NaHC03
When sodium is dissolved in liquid ammonia, a solution of deep blue colour is obtained. The colour of the solution is due to
(a) ammoniated electron
(b) sodium ion
(c) sodium amide
(d) ammoniated sodium ion
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.
When heated in air, the alkali metals form various oxides. Mention the oxides formed by Li, Na and K.
All compounds of alkali metals are easily soluble in water but lithium compounds are more soluble in organic solvents. Explain.