Among chalcogens,the correct order of amount of energy released during electron gain (electron gain enthalpy) is

Which of the following oxyacids of sulphur contains an $S-S$ linkage?

How many total statements are correct in the following?
$(i)$ $SO_2$ - antichlor,preservative
$(ii)$ $O_3$ - Disinfectant
$(iii)$ $Cl_2$ - Antiseptic
$(iv)$ $O_2$ - used in oxy-acetylene welding
$(v)$ $PH_3$ - used in smoke screens
$(vi)$ $HNO_3$ - Pickling of stainless steel

The test of ozone $O_3$ can be done by

Although oxygen is more electronegative than sulfur,$H_2S$ is acidic while $H_2O$ is neutral. This is because ..........

An element $X$ belongs to group $16$ and $5^{th}$ period. Its atomic number is