Question

Statement 1: the value of Avogadro’s constant is$6.022\times {{10}^{23}}$
Statement 2: Mole is the ratio of number of atoms present in the substance to the Avogadro number.
Now choose the correct option:
A.Only statement 1 is correct
B. Only statement 2 is correct
C. Both the statements are correct
D. Both the statements are incorrect

Answer 1

A mole is defined as a quantity that has Avogadro number of atoms which is $6.022\times {{10}^{23}}$. 1 mole of any element has a mass equal to their molar mass and the atoms equal to Avogadro number. Avogadro’s gave a hypothesis that stated that equal volume of all gases has equal number of molecules under similar temperature and pressure.

Complete answer:
As we know Avogadro’s hypothesis included that equal volume of all gases under the same condition of temperature of pressure has the same number of molecules. This leads to the discovery of moles, as 1 mole of any gas contains an equal number of atoms which is Avogadro’s number or ${{N}_{a}}$.
The value of Avogadro’s number came out to be$6.022\times {{10}^{23}}$ which is Avogadro’s constant. So, statement 1 is correct.
Number of moles can be given by dividing the total number of molecules or atoms by the Avogadro number of atoms. So, number of moles =$\dfrac{No.\,of\,molecules}{Avogadro\,number}$ or $n=\dfrac{N}{{{N}_{a}}}$. So, it is the ratio of number of atoms in a substance upon Avogadro number, thus this statement 2 is also correct,

Hence, the correct option is C as both the statements are correct.

Note:
The molar mass of any element is expressed in grams per mole due to the reason that the molar mass contains Avogadro number of atoms that is 1 mole. Also the number of moles of any substance can be determined by mass, as dividing the given mass of substance by its molar mass. So, the mass of 1 atom will be the atomic mass by the Avogadro number.