Answer:
A mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly
12 grams of carbon-12 (i.e., 6.023 X 1023).
Explanation:
The correct answer would be the last option. The property that is common to all group 2 elements is that they tend to form ionic bonds by losing electrons making these atoms positive charge. They are called cations. These elements are beryllium, magnesium, calcium, strontium, and radium.