Answer
a) $3S^{(+6)}O_{3} + {Al_{2}}^{(+3)}O_{3} \rightarrow {Al_{2}}^{(+3)}(S^{(+6)}O_{4})_{3}$
b) ${Cl_{2}}^{(+7)}O_{7} + H_{2}O \rightarrow 2HCl^{(+7)}O_{4}$
c) $Ca^{(+2)}O+Si^{(+4)}O_{2} \rightarrow Ca^{(+2)}Si^{(+4)}O_{3}$
Work Step by Step
a) $3S^{(+6)}O_{3} + {Al_{2}}^{(+3)}O_{3} \rightarrow {Al_{2}}^{(+3)}(S^{(+6)}O_{4})_{3}$
b) ${Cl_{2}}^{(+7)}O_{7} + H_{2}O \rightarrow 2HCl^{(+7)}O_{4}$
c) $Ca^{(+2)}O+Si^{(+4)}O_{2} \rightarrow Ca^{(+2)}Si^{(+4)}O_{3}$