Answer
The complete equation for that reaction is:
$Ca(s) + H_2SO_4(aq) -- \gt H_2(g) + CaSO_4(aq)$
Work Step by Step
$Ca(s)$ is a metal and $H_2SO_4$ is an acid. Therefore, this is a reaction between a solid metal and an acid, which will produce hydrogen gas $(H_2(g))$, and a salt.
$Ca(s) + H_2SO_4(aq) -- \gt H_2(g) + Salt$
The hydrogen gas only contains hydrogen (H), so the salt must be made of $Ca$ and $SO_4$.
The $Ca$ ion has a charge of $+2$, and $S{O_4}$ has that equal to: $-2$, so we would only need equal amounts to balance the charge of the ionic compound: $CaSO_4$
$Ca(s) + H_2SO_4(aq) -- \gt H_2(g) + Salt$
Now, we need to balance the equation. We can do that by putting a 2 before $HCl$:
$Ca(s) + H_2SO_4(aq) -- \gt H_2(g) + CaSO_4(aq)$
The equation is already balanced.
