Elements in the same group on the periodic table have the same number of valence electrons. The "groups" are the column (or rows). groups are vertically and periods are horizontally.
Answer:
Advantages
<u>Readily available at the moment </u>
<u>Relatively easy to produce energy from them</u>
Disadvantages
<u>Non-renewable source will eventually run out</u>
<u>Increasing fuel costs</u>
<u>Release carbon dioxide (CO 2 ) when burnt - greenhouse gas</u>
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