If a trivalent atom replaces a few silicon atoms in three dimensional network of silicon dioxide, what would be the type of charge on overall structure ?

Assertion (A): If aluminium atom s replace a few silicon atoms in three dimensional network of silicon dioxide, the overall structure acquries a negative charge. Reason(R): Aluminium is trivalent while silicon is tetravalent.

(A) ZSM-5 is used as a catalyst in petrochemical industries. (R) Zeolites are three-dimensional network silicates in which some atoms are replaced by luminium atoms.

impurity atoms with which pure silicon should be doped to make a p - type semiconductor are those of

each question constain STATEMENT-1(Assertion ) and STATEMENT - 2 (reason). examine the statement carefully and work the correct answer accoridng to the instructions given below : STATEMENT-1: ZSM-5 is a type of zeolites used as a catalyst in petrochemical industries. STATEMENT-2: Zeolites are microporous aluminusilicates three dimensional network silicates in which some silicon atoms are replaced by aluminium atoms.