Analytical techniques: explain question

The mass spectrum of an organic compound, Z, was recorded. The molecular ion peak is observed at m/z 84. The relative abundances of selected peaks are shown in the table.

There is also a fragment peak at m/z 29.

Explain how the mass spectrum of Z provides evidence for each of the following.

(i) The molecular mass of Z is 84. (ii) Z contains 5 carbon atoms. (iii) Z contains a chlorine atom. (iv) The fragment at m/z 29 is likely to be $\ce{C2H5+}$.