30 points

which example has 1.2×10^24 hydrogen atoms?

1 mole of water (h2o)
1 mole of methane (ch4)
2 moles of ammonia (nh3)
2 moles of hydrogen gas (h2)

1 mole of water

Explanation:

We know that the Avogadro's number is the amount of elemental units in any mole.

The Avogadro's number is

This means that for example, in a mole of atoms of hydrogen there are atoms of hydrogen.

To find in which example there are hydrogen atoms we first need to divide this number by the Avogadro's number :

≅ 2  ⇒

We need to find in which example there are 2 moles of atoms of hydrogen.

In one molecule of there are 2 atoms of hydrogen and 1 atom of oxygen. In terms of moles, in 1 mole of water there are 2 moles of atoms of hydrogen and 1 mole of atoms of oxygen.

The mole of water is the only example in which there are 2 moles of atoms of hydrogen ⇒  The correct option is 1 mole of