question_answer 85)

  In the following questions a statement of Assertion (A) followed by a statement of Reason (K) is given. Choose the correct option out of the choices given below each question. Assertion (A): If aluminium atoms replace a few silicon atoms in three dimensional network of silicon dioxide, die overall structure acquire a negative charge. Reason (R): Aluminium is trivalent while silicon is tetravalent. (a) Both A and R are correct and R is the correct explanation of A. (b)Both A and R are correct but R is not the correct explanation of A. (c) Both A and R are not correct. (d) A is not correct but R is correct.

Answer:

  (a) In aluminal silicates (anion), some of silicon atoms are replaced by aluminium. Since, aluminium is trivalent while silicon is tetravalent hence we get negatively charged ion.