JEE Advanced 2020 Full Test 7 Paper 1

Let the mass of acetaldehyde is xg, then mass of ethanol is (0.535−x)g. When acetaldehyde is heated with Fehling solution, it gives 1.2g of a red precipitate.
CH3CHO+2CuO→CH3COO−+‌

Cu

Redppt.

2O
∵143g of Cu2O is coming from =44g of CH3CHO
∴1.2g of Cu2O is coming from ‌

44

143

×1.2=0.37g of CH3CHO
% of CH3CHO=‌

0.37

0.535

×100=69.16%