Question

\[4mole\]of water is equal to:
A. $72g$ of water
B. $24.092 \times {10^{23}}$molecules of water
C. $48.184 \times {10^{23}}$atoms of hydrogens
D. All of the above.

Answer 1

Hint: First we must know that the molecular mass of \[{H_2}O\] is 18g. Therefore, we have to check all options for the correct answer. Also we know one mole of a substance is equal to $6.022 \times {10^{23}}$ units of that substance.

Complete answer: There are different ways to represent how much a mole of water is equal to. Therefore, it is important to check all the options provided before selecting a particular one.
The first option given to us is 72g. Now, we are well aware that 1mole of water is 18g. This is using the molecular formula H2O where the molecular weight of H is 1 and O is 16. Since there are two H and one O, we obtain the weight 18 (1+1+16). The molecular weight of any substance in grams is equal to one mole of it. Therefore, 1 mole of water has a molecular weight of 18g. Since there are 4 moles of water present, we simply multiply the two, 4x16=72.
This way, we can clearly see that the first option A is correct, as 4 moles of water is equal to 72g.
Now, coming to the next option, we can see that they have made use of Avogadro's number. The Avogadro’s number is equal to $6.022 \times {10^{23}}$ unit of a particular substance and is also the equivalent to one mole of that substance. So, one mole of water is equal to $6.022 \times {10^{23}}$units. Since there are 4 moles of water, we again multiply the number by 4 and obtain the result, $24.092 \times {10^{23}}$.
Therefore, now we can say that the second option B is correct as well.
Coming to the third option, we will again use Avogadro's number and we also know that 4 mole of water contains $24.092 \times {10^{23}}$ molecules of water. Also, one molecule of water contain 2 hydrogen atom in it so simply by multiplying the two we get, $2 \times 24.092 \times {10^{23}}$which will be equal to \[48.184 \times {10^{23}}\] atoms of hydrogen.
Therefore, the option C is also correct.
So, the answer to this will be option D. All of the above.

Note:
We must know that a mole can be equal to many forms such as mass, molecules, atoms or even the volume. At STP one mole of gas is equal to 22.4 litre of gas. Similarly, Avogadro’s one mole is equal to $6.022 \times {10^{23}}$ molecules/atoms of the given compound. In case of mass the molecular mass of the substance in grams is equal to 1 mole of substance.