One mole of an organic compound $\left(\mathrm{A}\right)$ with the formula ${\mathrm{C}}_3{\mathrm{H}}_8\mathrm{O}$ reacts completely with two moles of $\mathrm{HI}$ to form $\mathrm{X}$ and $\mathrm{Y}$. When $\mathrm{Y}$ is boiled with aqueous alkali it forms $\mathrm{Z}$. $\mathrm{Z}$ answers the iodoform test. The compound $\left(\mathrm{A}\right)$ is