LEVEL – 1
1. Name the alkali metal which form superoxide when heated in excess of air.
Ans: Potassium
2. LiCl is more soluble in organic solvent, why?
Ans: It is due to covalent in nature.
3. Explain why Sodium is less reactive than Potassium?
Ans: Due to less metallic character of sodium
4. Why are Potassium, and Cesium , rather lithium can be used in photoelectric cell ?
Ans: Due to lesser ionisation enthalphy.
5. Lithium is the only alkali metal to form nitride.
Ans: Due to diagonal relationship with Mg.
6. Name the radioactive element of group 1 and 2.
Ans: Fr and Ra
7. Explain why alkali and alkaline earth metals cannot be obtained by chemical reduction?
Ans: They are better reducing agent than C and CO.
LEVEL – 2
1. Explain the following :
(i) The mobility of the alkali metal ion in aqueous solution are :
(ii) Lithium is the only alkali metal to form nitride directly.
Ans: (i) The magnitude of hydration enthalphy decreases down the group so the size of the hydrated ion decreases down the group. (ii) Due to diagonal relationship with Mg.
2. ‘The chemistry of beryllium is not essentially ionic’. Justify the statement by making a reference of beryllium.
Ans: It is due to high polarising power of Be cation its compound are covalent in nature.
3. When alkali metal dissolves in liquid ammonia, the solution gives deep blue colour which is conducting in nature .Why?
Ans: Due to ammoniated cation and ammoniated electron.
4. Describe the three industrial uses of caustic soda.
Ans: Industrial uses of caustic soda:
(i) In soap industries
(ii) In the laboratory
(iii) In cotton industries.
5. Why it is necessary to add gypsum in the final stages of preparation of cement?
Ans: To increase the time of setting of the cement.
6. Beryllium and Magnesium do not give colour to flame whereas other alkaline earth metals do so why?
Ans: Due to high ionisation enthalpy of Be and Mg.
7. What happens when
(i) Sodium metal is dropped in water?
(ii) Sodium metal is heated in free supply of air?
(iii) Sodium peroxide is dissolved in water?
Ans: (i) NaOH is formed. (ii) Na2O2 is formed (iii) NaOH and H2O2is formed.
8. What happen when
(i) Calcium nitrate is heated?
(ii) Chlorine reacts with slaked lime?
(iii) Magnesium is burnt in air?
Ans: (i) CaO and O2 and NO2 (ii) bleaching powder is formed. (iii) MgO is formed.
EVEL – 3
1. Write balanced equation for the reaction between :
(i) KO2 and water
(ii) BeO + H2SO4
(iii) Ca(OH)2 + Cl2
2. Give a brief account of the following :
(i) Blue colour solutions of alkali metals in liquid ammonia.
(ii) Tendency to form divalent compounds of alkaline earth metals than monovalent.
(iii) Tendency to give flame colours by alkali metals.
Ans:
(i) Due to the presence of ammoniated electron.
(ii) In divalent oxidation state the octet is complete.
(iii) Due to less ionisation enthalpy of alkali metals.
