Answer:
c) 8.3 x 10^24 molecules
Explanation:
First of all, we convert the volume of the glass of water from mL to [tex]cm^3[/tex]:
[tex]V=250 mL = 250 cm^3[/tex]
The relationship between mass and volume is:
[tex]d=\frac{M}{V}[/tex]
where
[tex]d=1.00 g/cm^3[/tex] is the density of water
M is the total mass of the glass of water
[tex]V=250 cm^3[/tex] is the volume of the water in the glass
Solving for M,
[tex]M=dV=(1.00)(250)=250 g = 0.250 kg[/tex]
Now we know that the mass of a single molecule of water is
[tex]m=3.0\cdot 10^{-26}kg[/tex]
The total mass of the water in the glass can be written as
[tex]M=Nm[/tex]
where
N is the number of molecules in the glass of water
Solving for N, we find:
[tex]N=\frac{M}{m}=\frac{0.250}{3.0\cdot 10^{-26}}=8.3\cdot 10^{24}[/tex]
