Question

please answer with explanation and proper steps

Answer 1

Number of moles of solute(urea)    = n₁ =  6/60  = 0.1
Number of moles of solvent(water) = n₂ = 90/18 = 5

Relative lowering of vapour pressure = mole fraction of solute
                                                           = n₁/(n₁ +n₂)

but when n₁<<<<<n₂ as in this case

Relative lowering of vapour pressure is approximated as n₁/n₂
                                                                                        = 0.1/5
                                                                                        = 0.02

Hope u get helped by it