Question: how many grams of sodium chloride are present?
Answer: The concentration of 0.5 molar NaCl is half a mole per liter; then multiply by the quantity 1/4 liter (250 cm3) to get 1/8 moles NaCl. NaCl is approximately 58 grams per mole, so the amount of salt(NaCl) in the sample would be around 7.25 grams.