How many chlorine atoms are there in seven sodium chloride formula units?

The number of formula units of NaCl are 7. In 1 mole of NaCl there are formula unit are present.

Thus, 1 formula unit will be there in moles.

and, 7 formula unit will be there in moles.

There is 1 mol of Cl present in 1 mol of NaCl. thus, of Cl will be there in    mol of NaCl.

Converting number of moles into number of atoms as follows:

In 1 mole of a substance there are atoms of chlorine thus, in  mol there will be 7 atoms of chlorine.

Therefore, number of atoms of chlorine will be 7.

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of carbon is as shown here in the image.

fe 55.85 g/mol and h2o 18.02 g/mol.