Calculate the relative lowering of vapour pressure of solution containing 3 g urea in 50 g water. [molar mass of urea $=60 \mathrm{~g} \mathrm{~mol}^{-1}$ ]

Identify the type of defect in brass alloy.

What is the difference in molar masses of Undecane and Decane?

Which of the following is effectively used instead of DDT?