The gas produced on heating $MnO_2$ with conc. $HCl$ is

Which of the following halogens does not form oxoacids?

In aqueous solution, fluorine is a stronger oxidizing agent than chlorine. This is due to all of the following factors $EXCEPT$:

Which of the following statements regarding the properties of halogens are correct?
$(a)$ Due to small size and strong inter-electronic repulsion,the electron gain enthalpy of fluorine is less negative than that of chlorine.
$(b)$ Iodine has a different physical state and colour compared to other members of the group.
$(c)$ Fluorine does not show a positive oxidation state.
$(d)$ In $X_{2(g)} + H_2O(l) \rightarrow HX(aq) + HOX(aq)$ (where $X = Cl$ or $Br$).

Consider the following reactions:
$(A) (\text{Ionic halide}) + (B) (\text{Good oxidising agent}) + \text{conc. } H_2SO_4 \to (C) (\text{Red-Orange gas is evolved with few by-products})$
$(D) (\text{Other ionic halide}) + (B) + \text{conc. } H_2SO_4 \to (E) (\text{Has same colour as } (C))$
Which of the following properties are different for $(C)$ and $(E)$?

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