Which is the stable crystalline form of sulfur at room temperature?

Which of the following compounds does not liberate oxygen gas on warming with concentrated $H_2SO_4$?

Indicate the products $(X)$ and $(Y)$ in the following reactions:
$Na_{2}S + nS (n=1-8) \rightarrow (X)$
$Na_{2}SO_{3} + S \rightarrow (Y)$

What is true about $H_2S_nO_6$ (Polythionic acid)?

Why is a Tyndall box used in the manufacture of sulfuric acid by the contact process?

In the preparation of sulphuric acid,$V_2O_5$ is used in the reaction which is: