The compound, nah2po4, is present in many baking powders. what is its name? sodium phosphate sodium bephosphate sodium dihydrogen phosphate sodium hydrogen phosphate

 The  compound NaH2PO4     name  is

sodium  dihydrogen  phosphate

  Explanation
This name is    arrived  at  by using the   IUPAC rules  of naming   compound

1.  the metal (sodium)is  named  first  followed  by  the ligand ( hydrogen  and phosphate)

Ligand  are  molecules   that are   attached to  the metal  center.

2.   ligand  are  named using alphabetical   order(for  our  case  h  for hydrogen come before p for  phosphate hence hydrogen is named first)

3. Prefix   di is used  since hydrogen  are two

hence the name  of the compound  is  Sodium dihydrogen  phosphate

n = m / M

m = n × M

Nitrogen (N2) - a gas is always with an index 2 if we don't have shown how many molecules are there

m (N2) = 4,5 mol × (2×14.007 g/mol)

m (N2) = 4,5 mol × 28.014 g/mol = 126.063g

if you don't solve with the decimals in class just replace 14.007 with 14

also if you haven't learned abour gasses aways having index 2 then:

m (N2) = 4,5 mol × 14.007 g/mol = 63.0315g