The common form of periodic acid is $HIO_4 \cdot 2H_2O$ or $H_5IO_6$,which is known as:

$X_2$ 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 elements with atomic numbers $9, 17, 35, 53, 85$ are all

$HI$ cannot be prepared by the reaction of concentrated $H_2SO_4$ with $KI$ because:

Which of the following halogens is obtained from Caliche?

When chlorine water is exposed to sunlight,the colour change that occurs is: