$7.8 \mathrm{g}$ of a compound having molecular formula ${\mathrm{C}}_6{\mathrm{H}}_6$, on reacting with ${\mathrm{CH}}_3\mathrm{COCl}/{\mathrm{AlCl}}_3$ gives $8.4 \mathrm{g}$ of a product which has molecular formula ${\mathrm{C}}_8{\mathrm{H}}_8\mathrm{O}$. Calculate the percentage yield of the product ${\mathrm{C}}_8{\mathrm{H}}_8\mathrm{O}$. (Given atomic weights of $\mathrm{H}, \mathrm{C}$ and $\mathrm{O}$ respectively are $1,12$ and $16$)