Question

Which of the following statements about
the molecular mass is correct?
А
Molecular formula shows the
exact number of different types
of atoms present in a molecule
B
Molecular formula can be
obtained from empirical formula
if molar mass is known
С
Percentage composition of a
compound can be calculated
from its molecular formula
D
All the statements are correct​

Answer 1

The correct statement among the following statements about the molecular mass is:

(D) All the statements are correct

Reasons why all the given options are correct about molecular mass:

• Molecular mass is the total sum of the atomic mass of the atoms of that substance or element or compound.

Option A:

• Hence option a is correct as the molecular mass represents a particular formula that shows the exact number of different atoms present in a molecule.

Option B:

• The Empirical formula is the simplest ratio(which should be a whole number) of the atoms of the elements present in a compound.
• And if the molar mass is known then it can be divided by empirical formula mass to give the simplest whole number or close to it and then it is multiplied to the empirical formula.
• This gives the molecular formula of the compound.

Option C:

• If the molecular formula is given, then we can find the molecular mass. This mass of one element in one mole is divided by one whole mole of the compound, which gives the percentage composition by mass of the compound.