Question

?SiCl4(I) + ?H2O(I) = ?SiO2(S) + ?HCI(aq)​

Answer 1

SiCl4(L) + 2H2O(L) —>> SiO2(s) + 4HCl(aq)

We need balanced elements on both sides, products and reactants. We see from inspection we need to balance Cl, H, and O on both sides, reactants and products. So by adding 2moleH2O we need to add 4HCl to balance.

Answer 2

SiCl4 + 2H2O = SiO2 + 4HCl