Which of the following halogens does not form oxyacid?

Which of the following mineral acids can attack $SiO_2$?

Which of the following halogens does always show an oxidation state of $-1$?

At room temperature, the reaction between water and fluorine produces

In the following reaction,assign the nature of the product for the underlined atom upon complete hydrolysis at $R.T.$:
$\underline{I}_2 + H_2O \longrightarrow$ No reaction

As the atomic number of halogens increases,the halogens