Question

14. Assertion (A): If aluminium atoms replace a few silicon atoms in three dimensional network of silicon dioxide, the overall structure acquires a negative charge.
Reason (R) : Aluminium is trivalent while silicon is tetravalent.
(i) Both A and R are correct and R is the correct explanation of A.
(ii) Both A and R are correct but R is not the correct explanation of A.
(iii) Both A and R are not correct
(iv) A is not correct but R is correct.

Answer 1

Answer:

A is correct but R is not correct

Explanation:

Silicon will tend to form covalent bonds

so the question of positive or negative charge do not aris

Answer 2

The correct option is I) ie. Both assertion and reason are correct and B is explanation of A

In aluminium silicates some of the silicon atoms in the network are replaced by the aluminium atoms .

The aluminium atoms is trivalent whereas the silicon atom is tetravalent , therefore the structure acquires a negative charge due to excess of electrons.