Astatine is a

$X_2$ reacts with water to form $HX_{(aq)}$ and $HOX_{(aq)}$. $Y_2$ reacts with water to form $O_{2(g)}$,$Y^{-}_{(aq)}$ and $H^{+}_{(aq)}$. $Z_2$ does not react with water. $X_2, Y_2, Z_2$ are respectively

The correct decreasing order of boiling point of hydrogen halides is

Chlorine reacts with sodium hydroxide under various conditions to give:

Which of the following is the only existing oxoacid of fluorine?

Which of the following elements is in a liquid state at room temperature?