JEE Advanced levelSingle correct optionDifficulty 3 of 3mc068
11.5g of Na reacts with 21.3g of ClX2 in 2Na+ClX22NaCl (Na=23, Cl=35.5). The percent excess of the reagent in excess (relative to its stoichiometric requirement) and the mass of NaCl formed are
A16.7% and 29.25g
B20% and 35.10g
C20% and 29.25g
D40% and 14.62g
Answer: C
Na = 0.5 mol; ClX2 = 0.3 mol. Na needs 0.25 mol ClX2, so Na limits and ClX2 is in excess. Percent excess = (0.3 - 0.25)/0.25 x 100 = 20%. NaCl = 0.5 mol x 58.5 = 29.25 g.