[poshakpathak]

A 0.216 g sample of an aluminium compound X reacts with an excess of water to produce a
single hydrocarbon gas. This gas burns completely in O₂ to form H₂O and CO₂ only. The volume of CO₂ at room temperature and pressure is 108 cm³.
What is the formula of X?
A Al₂C₃
B Al₃C₂
C Al₃C₄
D Al₄C₃
I am lost on the first step. Im in high school and havent been taught reaction of carbon-containing Al compounds with water.

[AWK]

This is a common problem for students - remember everything. In chemistry, this is impossible. You have to remember a lot, but even more, you have to think and use the stored information extensively. It is finally "Cambridge International Advanced Subsidiary and Advanced Level".

First of all - aluminum and carbon show some typical valences, 3 and 4 respectively. This gives you the option of choosing only one aluminum-carbon compound. Excess of water suggests a hydrolysis reaction resulting in one hydrocarbon. All you need to do is make sure that the ratio of the number of CO₂ moles to the number of moles of the compound is equal to the carbon coefficient in that compound.

But here we have another problem - you need to read the 20-page Data Booklet and find out what "at room temperature and pressure" means - "V_m = 24.0 dm³mol^–1 under room conditions". For a one-hour exam of 40 questions (90 sec per question), at least information should be provided on which pages should be searched for additional information needed for this question.