The mass spectrum of an organic compound with the structure ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{CH}}_3$ is shown.

Identify the fragments with mass/charge ratios of 

i. $15$    ii. $29$   iii. $43$   iv. $58$

An organic compound, $\mathrm{Z}$, has a molecular ion peak, $\mathrm{M}$, with a reactive abundance of $36.4\%$ and an $\left[\mathrm{M}+1\right]$ peak with a relative abundance of $4.8\%$. Deduce the number of carbon atoms this compound contains.

The mass spectrum of chlorobutane shows an $\left[\mathrm{M}+2\right]$ peak beyond the ${\mathrm{M}}_{\mathrm{r}}$ peak. Explain why there is an $\left[\mathrm{M}+2\right]$ peak.

The relative height of the $\left[\mathrm{M}+2\right]$ peak in organic compound $\mathrm{T}$ is the same as that of the ${\mathrm{M}}_{\mathrm{r}}$ peak. Explain how this shows that the compound contains one atom of bromine and not one atom of chlorine.