Question

One uranium atom has a mass of 3.95 x 10^-22 grams.

Answer 1

Remember
(ab)/(cd)=(a/c)(b/d)
and
$\frac{x^n}{x^m}=x^{n-m}$

1kg=1000g=1*10^3g
hmm, I estimate, 4 of them

x=number of attoms
mass of 1 times x=1*10^3
3.95*10^-22 times x=1*10^3
divide both sides by 3.95*10^-22
x=$\frac{1*10^3}{3.95*10^{-22}}= (\frac{1}{3.95} )( \frac{10^{3}}{10^{-22}} )$=$0.25316*10^{25}$=$2.5316*10^{24}$
a million has 9 zeroes
so 24 zeroes is alot that is a septillion, so there are 2.5316 septillion uranium atoms in 1kg


a. 4
b. underestimate