Propane molecule on chlorination under photochemical condition gives two di-chloro products, " $x$ " and " $y$ ". Amongst " $x$ " and " $y$ ", " $x$ " is an optically active molecule. How many tri-chloro products (consider only structural isomers) will be obtained from " x " when it is further treated with chlorine under the photochemical condition?

The incorrect statement among the following is

The correct stability order of the following species/molecules is :

$2.8 \times 10^{-3} \mathrm{~mol}$ of $\mathrm{CO}_2$ is left after removing $10^{21}$ molecules from its ' $x$ ' mg sample. The mass of $\mathrm{CO}_2$ taken initially is Given: $\mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}$