Final answer:
The mass of 0.015 millimoles of acetone is -300,000 nanograms.
Step-by-step explanation:
To find the mass of 0.015 millimoles (mmol) of acetone, we can use the molar mass of acetone and the given number of moles. The molar mass of acetone is 58.1 g/mol, so the mass of 1 mole of acetone is 58.1 g.
Since 0.015 mmol is a very small fraction of a mole, we would expect the mass to be about one-ten thousandth of the molar mass, which is -0.02 g.
In nanograms, the mass of 0.015 mmol of acetone is -0.02 g x 1,000,000,000 ng/g x 0.015 mmol/mol = -300,000 ng.