question_answer

Which of the following statements about  noble gases are correct? (i) \[\text{Xe}{{\text{O}}_{\text{3}}}\]  is  an  explosive  tetrahedral molecule. (ii) In Fisher Ringes method, a mixture of \[\text{CaC}{{\text{l}}_{\text{2}}}\] and \[\text{Ca}{{\text{C}}_{\text{2}}}\] is used to remove \[{{\text{N}}_{\text{2}}}\] and \[{{\text{O}}_{2}}.\] (iii) He and Ne are chemically inert due to lack of d-orbitals and high ionization potential. (iv) At 173 K He and Ne are adsorbed on activated charcoal. The correct answer is

A)  I and II                                

B)  II and III

C)  II, III and IV       

D)  I, II, III and IV

Correct Answer: B

Solution :

                 \[\text{Xe}{{\text{O}}_{\text{3}}}\]is an explosive pyramidal molecule due to presence of one lone pair of electron. (II) In Fisher Ringes method, the oxygen and nitrogen of air are removed by passing it over a mixture of calcium carbide and calcium chloride. (Ill) He and Ne both have high ionization energy and lack of d-orbitals, so they are chemically inert. (IV) Except He all inert gases are adsorbed on activated charcoal and the extent of adsorption increases on moving down the group. Hence, only statement (II) and (III) are correct for noble gases.