1.The correct statement(s) about surface properties is (are) A) The critical temperature of ethane and nitrogen are 563 K and 126 K. respectively. The absorption of ethane will be more than that of nitrogen of the same amount of activated charcoal at a given temperature B) Cloud is an emulsion type of colloid in which liquid is dispersed phase and gas is dispersion medium C) Adsorption is accompanied by decreases in enthalpy and decreases in entropy of the system D) Brownian motion of colloidal particles does not depend on the size of the particles but depends on the viscosity of the solution View Answer Report DiscussAnswer: Option A,CExplanation:(b) Higher the critical temperature, greater the extent of adsorption (b) P(s) + Q (g) → PQ(s) adsorbent Adsorbate As gaseous adsorbate is adsorbed on a solid surface, entropy decreases. Also formation of the bond between P and Q results in release of energy, hence ΔH<0
2.The option (s) with only amphoteric oxides is (are) A) $NO,B_{2}O_{3},PbO,SnO_{2}$ B) $Cr_{2}O_{3},CrO,SnO,PbO$ C) $Cr_{2}O_{3},BeO,SnO,SnO_{2}$ D) $ZnO,Al_{2}O_{3},PbO,PbO_{2}$ View Answer Report DiscussAnswer: Option C,DExplanation:(c) is incorrect because NO is the neutral oxide (d) is incorrect because CrO is a basic oxide
3.Among the following , the correct statement(s) is (are) A) $Al(CH_{3})_{3}$ has the three centre two -electron bonds in its dimeric structure B) The lewis acidity of $BCl_{3}$ is greater than that of $AlCl_{3}$ C) $AlCl_{3}$ has the three centre two electron bonds in its dimeric structure D) $BH_{3}$ has the three centre two electron bonds in its dimeric structure View Answer Report DiscussAnswer: Option A,B,DExplanation:(a) (b) (c) BCl3 is stronger Lewis acid than AlCl3 due to greatest extent of $P_{\pi}-P_{\pi}$ back bonding in AlCl3 (d)
4.For the following compounds, the correct statement(s) with respect to nucleophilic substitution reaction is(are) A) Compound IV undergoes inversion of configuration B) The order of reactivity for I, III, and IV is :IV >I >III C) I and III follow $S_{N}1$ mechanism D) I and II follow $S_{N}1$ mechanism View Answer Report DiscussAnswer: Option C,DExplanation:(a) Both I and II are 10 halides, undergoes SN 2 reaction. (b) III is a tertiary halide, undergoes SN 2 reaction. I is benzylic bromide, it is very reactive in SN 1 also as if produces stable benzylic carbonation.
5.In a bimolecular reaction, the steric factor P was experimentally determined to be 4.5. the correct option(s) among the following is (are) A) The activation energy of the reaction is unaffected by the value of the steric factor B) The experimentally determined value of the frequency factor is higher than that predicted by Arrhenius equation C) The value of the frequency factor predicted by Arrhenius equation is higher than that determined experimentally D) Since P=4.5 the reaction will not proceed unless an effective catalyst is used View Answer Report DiscussAnswer: Option A,BExplanation:If the steric factor is considered the corrected Arrhenius equation w $k= pAe^{\frac{-Ea}{RT}}$ where A= frequency factor by Arrhenius p>1, pA>A hence , (a) is correct Activation energy is not related to steric factor
