Molarity is defined as number of moles of solute in 1 L solution
molarity of the NaCl solution is 1.20 M
in 1 L NaCl solution there are 1.20 mol
therefore in 250 mL solution there are - 1.20 mol/L x 0.250 L = 0.30 mol
there are 0.3 mol of NaCl in 250 mL
the answer is 5) 0.3 mol
