Q26 of 30 Page 1

A metal ‘M’ is stored under kerosene. It vigorously catches fire, if a small piece of this metal is kept open in air. Dissolution of this metal in eater release great amount of energy and the metal catches fire. The solution so formed turns red litmus blue.

(a) Name the metal ‘M’


(b) write formula of the compound formed when this metal is exposed to air.


(c) Why is metal ‘M’ stored under kerosene?


(d) If oxide of this metal is treated with hydrochloric acid, what would be the products?


(e) Write balanced equations for:


(i) Reaction of ‘M’ with air.


(ii) Reaction of ‘M’ with water.


(iii) Reaction of metal oxide with hydrochloric acid.


OR


(a) Write electro dot structures of Ca (At. No. 20) and O (At. No. 8).


(b) Show the formation of calcium oxide by transfer of electrons.


(c) Name the ions present in the compound.


(d) List four important characteristics of this compound.


(A) Sodium

(B) Sodium Oxide Na2O


4Na+O2→2Na2O


(C) Sodium metal is kept in kerosene oil to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and forms Sodium hydroxide which is a highly exothermic reaction.


2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) + heat energy


(d) Sodium oxide reacts with hydrochloric acid to produce sodium chloride and water.


Na2O + 2HCl → 2NaCl + H2O


(e) (i) 4Na + O2→ 2Na2O


(ii) 2Na + 2H2O → 2NaOH + H2


(iii) Na2O + 2HCl → H2O + 2NaCl


OR


(A)


AND


(B)



(C)Calcium ion and oxygen ion


(d) It is an ionic compound having properties :


1. They have high melting and boiling points.


1. They are hard.


2. They have high electrical conductivity.


3. They form crystals.


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