The empirical formula weight of ' $Z$ ' in the given reaction sequence is n-propyl bromide $\xrightarrow[\text { Dry ether }]{\mathrm{Na}} \mathrm{X} \xrightarrow[\substack{773 \mathrm{~K} \\ 20 \mathrm{~atm}}]{\mathrm{V}_2 \mathrm{O}_5} \mathrm{Y} \xrightarrow[\substack{\mathrm{UV} \\ 500 \mathrm{~K}}]{\mathrm{Cl}_2} \mathrm{Z}$

• A

  $47.5$
• B

  $54.5$
• C

  $84.5$
• Correct answer
  D

  $48.5$

Hence, the correct answer is option: 'D'.