Answer
(a) $SiCl_4 + 2H_2O -- \gt SiO_2 + 4HCl$
(b) $P_4O_{10} + 6H_2O -- \gt 4H_3PO_4$
(c) $CaCN_2 + 3H_2O -- \gt CaCO_3 + 2NH_3$
(d) $3NO_2 + H_2O -- \gt 2HNO_3 + NO$
Work Step by Step
(a)
Balance the $Cl$ compounds on each side:
$SiCl_4 + H_2O -- \gt SiO_2 + 4HCl$
Balance the hydrogen compounds:
$SiCl_4 + 2H_2O -- \gt SiO_2 + 4HCl$
(b)
Balance the $P$ compounds on each side:
$P_4O_{10} + H_2O -- \gt 4H_3PO_4$
Balance the $H$ compounds on each side:
$P_4O_{10} + 6H_2O -- \gt 4H_3PO_4$
(c)
Balance the $N$ compounds on each side:
$CaCN_2 + H_2O -- \gt CaCO_3 + 2NH_3$
Balance the $H$ compounds:
$CaCN_2 + 3H_2O -- \gt CaCO_3 + 2NH_3$
(d)
Balance the $H$ compounds on each side:
$NO_2 + H_2O -- \gt 2HNO_3 + NO$
To balance the equation, we just need 2 more $N$ and 4 more oxygens on the left side; therefore, we can just add 2 more $NO_2$.
$3NO_2 + H_2O -- \gt 2HNO_3 + NO$
