It actually depends on the percentage of the concentration give. Percentages can be expressed as %mass/mass, %volume/volume or %mass/volume. To keep things simple, let's just assume that it is in %volume/volume. Thus, 13% of 520 mL is pure acid.
Volume of pure acid = 520*0.13 = 67.6 mL
Answer: There are 
molecules present in 7.62 L of 
at 
and 722 torr.
Explanation:
Given : Volume = 7.62 L
Temperature = 
Pressure = 722 torr
1 torr = 0.00131579
Converting torr into atm as follows.
Therefore, using the ideal gas equation the number of moles are calculated as follows.
PV = nRT
where,
P = pressure
V = volume
n = number of moles
R = gas constant = 0.0821 L atm/mol K
T = temperature
Substitute the values into above formula as follows.
According to the mole concept, 1 mole of every substance contains 
atoms. Hence, number of atoms or molecules present in 0.244 mol are calculated as follows.
Thus, we can conclude that there are molecules present in 7.62 L of at and 722 torr.
Answer: 568g/mol
Explanation:
It should be noted that there are 40 atoms of carbon in lycopene.
Since mass of 1 carbon = 12g/mol
Mass of 40 carbon atoms = 40 × 12g/mol = 480g/mol
Let the molar mass of lycopene be represented by x.
Therefore the molar mass of carbon = x × mass percent of carbon in lycopene
x × 84.49% = 480g/mol
x × 0.8449 = 480g/mol
x = 480/0.8449
x = 568g/mol
The molar mass of lycopene is 568g/mol
