Answer
(a) $10^{12}$ protons
(b) $10^{10}$ protons
(c) $10^{29}$ protons
(d) $10^{68}$ protons
Work Step by Step
(a) The number of protons in a bacterium is: $\frac{10^{-15} ~kg}{10^{-27}~kg/proton} = 10^{12}~protons$
(b) The number of protons in a DNA molecule is: $\frac{10^{-17} ~kg}{10^{-27}~kg/proton} = 10^{10}~protons$
(c) The number of protons in the human body is: $\frac{10^{2} ~kg}{10^{-27}~kg/proton} = 10^{29}~protons$
(d) The number of protons in our galaxy is: $\frac{10^{41} ~kg}{10^{-27}~kg/proton} = 10^{68}~protons$
