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ICSE Class 9 Chemistry Question 17 of 20

The Periodic Table — Question 6

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Question

Question 6

(a) Name the alkali metals. How many electrons(s) do they have in their outermost orbit.

(b) Take any one alkali metal and write its reaction with

(i) Oxygen

(ii) Water

(iii) Acid

Answer

(a) Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr) are alkali metals. They have 1 electron in their outermost orbit.

(b) (i) Alkali metal like sodium reacts rapidly with oxygen forming metal oxide

4Na + O2 ⟶ 2Na2O

(ii) Alkali metal like sodium reacts with water violently and produces its hydroxide and hydrogen

2Na + 2H2O ⟶ 2NaOH + H2

(iii) Alkali metal react violently with dil. HCl and dil. H2SO4 to produce hydrogen

2Na + 2HCl ⟶ 2NaCl + H2