16.The complex showing a spin-only magnetic moment of 2.82 B.M. is: A) $Ni(CO)_{4}$ B) $[NiCl_{4}]^{2-}$ C) $Ni(PPh_{3})_{4}$ D) $[NiCN_{4}]^{2-}$ View Answer Report DiscussAnswer: Option BExplanation:$[NiCl_{4}]^{2-}$, O.S. of Ni = +2 Ni(28) = 3d8 4S2 No. of unpaired electrons = 2 Magnetic moment, μ = 2.82 B.M.
17.For the reaction 2N2O5 → 4NO2 + O2, rate and rate constant are 1.02 x 10-4 mol lit-1 sec-1 and 3.4 x 10-5 sec-1 respectively then concentration of N2O5, at that time will be A) 1.732 M B) 3 M C) $3.4\times10^{5}$ D) $1.02\times10^{-4}$ View Answer Report DiscussAnswer: Option BExplanation:2N2O5 → 4NO2 + O2 from the unit of rate constant it is clear that the reaction follow first order kinetics. Hence by rate law equation r = k [N2O5] where r = 1.02 x 10-4, k = 3.4 x 10-5 1.02 x 10-4 = 3.4 x 10-5 [N2O5] [N2O5] = 3M
18.In a compound, atoms of element Y form ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be A) $X_{4}Y_{3}$ B) $X_{2}Y_{3}$ C) $X_{2}Y$ D) $X_{3}Y_{4}$ View Answer Report DiscussAnswer: Option AExplanation:From the given data, we have Number of Y atoms in a unit cell = 4 Number of X atoms in a unit cell = 8×2/3 = 16/3 From the above we get the formula of the compound as X16/3Y4 Or X4 Y3
19.The radius of La3+ (Atomic number of La=57) is 1.06 Å. Which one of the following given values will be closest to the radius of Lu3+ (Atomic number of Lu = 71)? A) 1.40 Å B) 1.06Å C) 0.85 Å D) 1.60 Å View Answer Report DiscussAnswer: Option CExplanation:$Ionic radii \propto \frac{1}{z}$ $Thus \frac{z_{2}}{z_{1}}\Rightarrow\frac{1.06}{(Ionic radii of Lu^{3+})} = \frac{71}{57}$ Ionic radii of Lu3+ = 0.85Å
20.The resistance of 0.01 N solution of an electrolyte was found to be 220 ohm at 298 K using a conductivity cell with a cell constant of 0.88cm-1. The value of equivalent conductance of solution is - A) $400 mho$ $cm^{2} g$ $ eq^{-1}$ B) $295 mho$ $cm^{2} g$ $ eq^{-1}$ C) $ 419 mho$ $cm^{2} g$ $ eq^{-1}$ D) $425 mho$ $cm^{2} g$ $eq^{-1}$ View Answer Report DiscussAnswer: Option AExplanation:$Λ_{eq}=K\times\frac{1000}{N}=\frac{1}{R}\times\frac{l}{a}\times\frac{1000}{N}$ = $\frac{1}{R}\times Cell constant\times\frac{1000}{N}$ = $\frac{1}{220}\times0.88\times\frac{1000}{0.01}$ = $400 mho$ $cm^{2} g$ $eq^{-1}$
