I would say there is 10 (2 in the ethyl group, 3 in the three methyl groups and 5 in the pent chain)
Answer:
B. using efficient light bulbs
D. Has a uniform composition and is only able to be separated by chemical means.
B, the height above or below sea level
Answer:
The number before any molecular formula applies to the entire formula. So here you have five molecules of water with two hydrogen atoms and one oxygen atom per molecule. Thus you have ten hydrogen atoms and five oxygen atoms in total.
