The formula of a compound that is formed by the aluminium and sulphur is-

1.  AlS₂
2.  Al₂S₃
3.  Al₃S₂
4.  Al₃S₄

The oxidation state and covalency of Al in [AlCl(H₂O)₅]²⁺ are respectively:

1. +3 and 3
2. +6 and 2 
3. +3 and 6
4. +2 and 2 

Consider the following reaction.
Na₂O + H₂O → A
Cl₂O₇ + H₂O → B
The product A and B are respectively-
1. A is NaOH; and B is HOCl
2. A is NaH; and B is HOCl
3. A is NaH; and B is HClO₂ 
4. A is NaOH; and B is HClO₄