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
(a) Due to least electropositive character or least basicity of Be, BeC03 is less stable and hence decomposes to give BeO and C02.
BeC03→BeO + C02
Since the decomposition reaction is reversible, therefore, to increase the stability of BeC03 or to reverse the above equilibrium, BeC03 is kept in an atmosphere of C02.
Lithium resembles magnesium in some of its properties. Mention two such properties and give reasons for this resemblance.
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 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 |
(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?
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
Explain why can alkali and alkaline earth metals not be obtained by chemical reduction method.
Write balanced equations for reactions between.
(a) Na2O2 and water
(b) KO2 and water
(c) Na2O and CO2
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.
Why are BeS04 and MgS04 readily soluble in water while CaS04, SrS04 and BaS04 are insoluble?
Arrange the following in the increasing order of solubility in water.
MgCl2, CaCl2, SrCl2, BaCl2
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
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 |
Which one of the following alkali metals give hydrated salts?
(a) Li (b) Na (c) K (d) Cs
Name the alkaline earth metals whose salt do not impart colour to a non-luminous flame.
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
A chemical A is used for the preparation of washing soda to recover ammonia. When C02 is bubbled through an aqueous solution of A, the solution tons milky. It is used in white washing due to disinfectant nature. What is the chemical formula of A?
(a) Ca(C03)2
(b) CaO
(c) Ca(OH)2
(d) CaC03
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.
Match the compounds given in Column I with their uses mentioned in Column II.
| Column I | Column II |
| (i) CaC03 | (a) Dentistry, ornamental work |
| (ii) Ca(OH)2 | (b) Manufacture of sodium carbonate from caustic soda |
| (iii) CaO | (c) Manufacture-of high quality paper |
| (iv) CaS04 | (d) Used in white washing |
Describe two important uses of each of the following: ,
(i) caustic soda (ii) sodium carbonate (iii) quick lime
Why are ionic hydrides of only alkali metals and alkaline earth metals are known? Give two examples.
(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.
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.
Compare the alkali metals and alkaline earth metals with respect to (i) ionization enthalpy, (ii) basicity of oxides, (iii) solubility of hydroxides.
Explain the significance of sodium, potassium, magnesium and calcium in biological fluids.
What is the effect of heat on the following compounds (Give equations for the reactions)? (i) CaC03 (ii) CaSO4 2H2O
Write the chemical formula of the following compounds.
(i) Chile salt petre (ii) Marble (iii) Brine
Which out of the following can be used to store an alkali metal?
H2O, C2H5OH and Benzene
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
When alkali metal dissolves in liquid ammonia, the solution can acquire different colours. Explain the reason for this type of colour change.
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.
Why are alkali metals always univalent? Which alkali metal ion forms largest hydrated ion in aqueous solution?
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)2C03 with sodium chloride? Explain.