Gas Percentage by volume methane 90 ethane 5 propane 3 other gases 2 The table shows the approximate composition of a sample of natural gas taken from a gas...
Question 1 Report
| Gas | Percentage by volume |
|---|---|
| methane | 90 |
| ethane | 5 |
| propane | 3 |
| other gases | 2 |
The table shows the approximate composition of a sample of natural gas taken from a gas field. A student uses the data to identify which alkane makes up the greatest proportion of natural gas.
Answer Details
Read straight down the percentage column and compare the values: 90 per cent, 5 per cent, 3 per cent and 2 per cent. The largest share by a very wide margin is 90 per cent, so the alkane present in the greatest proportion is methane, \(\text{CH}_4\), the simplest member of the series.
Ethane at 5 per cent and propane at 3 per cent are minor components, so choosing either misreads the ranking. The other gases entry at 2 per cent is the smallest figure and is not even a single named alkane, so it cannot be the answer to a question asking which alkane dominates.
Note the useful check that the four percentages sum to 100, confirming the table accounts for the whole sample.
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