Challenge problem. At room temperature, a binary compound X is a very toxic colorless gas with acrid smell. The aqueous solution of X is a weak and highly corrosive monobasic acid.

a$)$ Determine the molecular formula of X if it contains $95\%$ of an unknown element Y by mass.

b$)$ At room temperature, gas X has $60$ times higher density than H$2.$ Explain.

c$)$ What is a unique requirement for storage of aqueous solution of X$?$ Explain