Question

How many atoms of carbon are in 20 molecules of glucose, `C_6H_12O_6`?

Answer 1

120

Explanation:

One molecule of glucose has 6 atoms, as you can see in carbon's index.( `C_6`).
In 20 molecules there will be `6*20` carbon atoms.
It can also be written down as:
20 `C_6H_12O_6`
So, written down like this there are `20*6` carbon molecules, `12*20` hydrogen atoms and `6*20` oxygen molecules.