Question

Which statement best describes a mole?

It is 12 units of a given substance.

It contains 6.02 mc001-1.jpg 1023 grams of sodium chloride.

It is the mass of 12 carbon atoms.

It contains 6.02 mc001-2.jpg 1023 particles of a given substance.

Answer 1

Answer : The correct option is, It contains
`6.02* 10^(23)` particles of a given substance.

Explanation :

According to the mole concept, one mole of a substance contains
`6.02* 10^(23)` number of particles of a given substance.

For example :

1 mole of oxygen (O) contains
`6.02* 10^(23)` number of oxygen atoms

1 mole of oxygen
`(O_2)` contains
`2* 6.02* 10^(23)` number of oxygen atoms

Hence, the correct option is, It contains
`6.02* 10^(23)` particles of a given substance.

Answer 2

It contains 6.02mc001-2.jpg particles of a given substance is the answer. A mole is simply a unit of measurement. Units are invented when existing units are inadequate. Chemical reactions often take place at levels where using grams wouldn't make sense, yet using absolute numbers of atoms/molecules/ions would be confusing.