Question

If the numerical value of one mole is equal to the total number of electrons present in one molecule of carbon dioxide then the total number of molecules present in 0.1 mole of oxygen gas is:
(1) 4.4
(2) 2.2
(3) \[6.022 \times {10^{22}}\]
(4) \[6.022 \times {10^{23}}\]

Answer 1

Hint: The SI unit to measure the quantity of any chemical entity is mole. Avogadro number is \[6.022 \times {10^{23}}\]. This number means that in a mole of any chemical species, there is the presence of\[6.022 \times {10^{23}}\]atoms.

Complete Step by Step Solution:
Here, one mole equals the electron number in one molecule of carbon dioxide. Therefore, we have to find out the number of electrons in carbon dioxide first.
Carbon has the atomic number of 6 and Oxygen has the atomic number of 8.
So, the number of electrons in \[{\rm{C}}{{\rm{O}}_{\rm{2}}}\] =\[6 + 2 \times 8 = 6 + 16 = 22\]
Therefore, the number of electrons in Carbon dioxide is 22.
So, this means that one mole in the given question is 22.
Now, it is time to find out the number of molecules in \[0.1\]mole of Oxygen gas.

We find 1 mole=22 molecules.
Therefore, 0.1 mole=\[22 \times 0.1 = 2.2\] molecules.
Hence, option (2) is right.

Additional Information:
To find out the quantity of moles of any chemical entity, there are many formulas such as,
Number of moles=Mass/Molar mass
Another formula is,
Number of moles=Number of atoms/Avogadro number
In this way, we can find out the mole number, if the mass and number of atoms are given.

Note: The formula of Oxygen gas is \[{{\rm{O}}_{\rm{2}}}\] . Its atomic mass is 32 g and it possesses \[6.02{\rm{ }} \times {\rm{1}}{{\rm{0}}^{23}}\] molecules. But the number of atoms in \[{{\rm{O}}_{\rm{2}}}\] is \[12.04{\rm{ }} \times {10^{23}}{\rm{ }}\left( {2{\rm{ }} \times {\rm{ }}6.022 \times {\rm{ }}{{10}^{23}}} \right)\] atoms as each Oxygen molecule has two atoms of Oxygen.