Metal A has electronic configuration of 2, 8, 1 and metal B has 2, 8, 8, 2. [5 MARKS]
(a) Identify A and B.

(b) Give the effect of heat on their:
(i) oxides
(ii) hydroxides
(iii) carbonates

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Solution

a) 2 Marks
b) 3 Marks

(a) The metal A having electronic configuration : 2, 8, 1
$∴$ its atomic no., Z = 2 + 8 + I = 11
Hence it is sodium (Na).
The metal B having electronic configuration : 2, 8, 8, 2
$∴$ its atomic no., Z = 2 + 8 + 8 + 2 = 20
Hence it is calcium (Ca).

(b) i) Action of heat on their oxides: There is no effect of heat on sodium oxide and calcium oxide.

ii) Action of heat on their hydroxides: There is no effect of heat on sodium hydroxide. However, calcium hydroxide decomposes on heating.
$C a (O H)_{2} h e a t - - \to C a O + H_{2} O$

iii) Action of heat on their carbonates: There is no effect of heat on sodium carbonate. However, calcium carbonate decomposes on heating.
$C a C O_{3} h e a t - - \to C a O + C O_{2}$

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Similar questions

Metal A has an electronic configuration of 2,8,1 and metal B has 2,8,8,2 which is a more reactive metal.

(a) Identify A and B and give their reactions with dil.HCl and dil. $H_{2} S O_{4}$ .

(b) Give the effect of heat on their:

(i) oxides, (ii) hydroxides,

(iii) carbonates, (iv) nitrates.

A

2, 8, 1

2, 8, 2

A

B

A

_{2}

_{4}

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