A fairly straight forward calculation, but care needs to be taken to draw the diagram correctly and making sure you do the math correctly.

**A. **4 C (graphite) +
5 H_{2} (gas) --> CH_{3}CH_{2}CH_{2}CH_{3}
(gas)

**B.** (CH_{3})_{3}CH
(gas) + 13/2 O_{2}
(gas) --> 4 CO_{2 }(gas) + 5 H_{2}O
(gas)

**C.**

**D.** The
calculation is shown on the figure above.
The steps are :

(i) calculate the number of moles of 2-methylpropane in 6.37g

(ii) calculate the ΔH_{c}/ mol for 2-methylpropane by dividing the heat given by part (i)

(iii) calculate the ΔH_{c}/ mol for butane by recognising that ΔH_{f }+ ΔH_{c}must be the same for the two isomers.