Ar, Mr and Mole

Select the statements that are key concepts for relative atomic mass, Ar.

1. 1. carbon-12 atom is used as the standard atom for relative masses.

2. 2. relative atomic mass is a ratio and therefore has no units.

3. 3. Ar values are given in the periodic table.

4. 4. Ar values may not be whole numbers as elements exist as a mixture of isotopes.

• 1 and 2

• 2 and 3

• 2, 3 and 4

• 1, 2, 3 and 4

What of the following are true about relative formula mass?

1. 1. It is the relative molecular mass for an ionic compound.

2. 2. It has no unit like relative molecular mass.

3. 3. It is calculated in the same way as relative molecular mass.

• 1 and 2

• 2 and 3

• 1,2 and 3

How many hydrogen molecules are there in 3 mole?

• 3 hydrogen molecules

• 18 hydrogen molecules

Fill in the blanks.

From the table, molar mass of a substance is ............. to its relative molecular mass, Mr in ................

There is a bag of corn kernels. A cook wants to know the number of kernels in it.

Write down the steps to find the number of corn kernels in the bag.