Name the compound (NH₄)₂SO₄

Q. The name of the $(N{H}_4{)}_{2}S{O}_4$ compound is

Q. Which compound is missing in the reaction given below?
$2NaOH+(N{H}_4{)}_{2}S{O}_4\to ?+N{a}_{2}S{O}_4+2H_{2}O$

Q. How many compounds liberate $N{H}_3$ on heating from the following?
$(N{H}_4{)}_{2}S{O}_4$, $(N{H}_4{)}_{2}C{O}_3$, $N{H}_{4}Cl$, $N{H}_{4}N{O}_3$, $(N{H}_4{)}_{2}C{r}_2{O}_7$

Q. The compound whose 0.1 M solution at ${25}^{\circ }C$ is basic is :