Compound $\text{'}\mathrm{A}\text{'}$ (molecular formula ${\mathrm{C}}_3{\mathrm{H}}_8\mathrm{O}$) is treated with acidified potassium dichromate to form a product $\text{'}\mathrm{B}\text{'}$ (molecular formula ${\mathrm{C}}_3{\mathrm{H}}_6\mathrm{O}$). $\text{'}\mathrm{B}\text{'}$ forms a shining silver mirror on warming with ammoniacal silver nitrate. $\text{'}\mathrm{B}\text{'}$, when treated with an aqueous solution of ${\mathrm{H}}_2{\mathrm{NCONHNH}}_2\mathrm{HCl}$ and sodium acetate, gives a product $\text{'}\mathrm{C}\text{'}$. Identify the structure of $\text{'}\mathrm{C}\text{'}$.