Q1 of 47 Page 1

A cube solid is made up of two elements A and B. The elements of A forms hcp while atoms of element B occupy two-third of the octahedral voids. What is the formula of the solid?

Let the no. of atoms of A forming the hcp be x


So, the no. of octahedral voids = x


And the no. of tetrahedral voids = 2x


As the atoms of element A forms HCP and atoms of B occupies 2/3 of the octahedral voids, so the ratio of atoms of A and B are x:(2/3)x


• A:B=3:2


• The formula of the solid is A3B2


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26

Give reasons for the following :

(a) NO2 dimerises readily.


(b) Chlorine acts as a bleaching agent.


(c) In spite of small size, electron gain enthalpy of oxygen is less


negative as compared to sulphur.


(d) Unlike chlorine, fluorine forms only one oxoacid, HOF.


(e) Noble gases have very low boiling points.


OR


(a) Draw structure and name the shape of the following :


(i) SF4


(ii) ICl3


(b) What happens when (Support your answer with equation)


(i) Chlorine gas is passed through hot and concentrated sodium


hydroxidesolution ?


(ii) Xenon hexafluoride is subjected to complete hydrolysis ?


(iii) Concentrated sulphuric acid is poured over cane sugar ?


 27

(a) Give IUPAC name of CH3 – CH = CH – CHO.

(b) How can you distinguish between ethanol and ethanal ?


(c) How will you convert the following :


(i) Toluene to benzoic acid


(ii) Ethanol to propan-2-ol


(iii) Propanal to 2-hydroxypropanoic acid


OR


(a) Give IUPAC name of Salicylic acid.


(b) Chloroacetic acid is more acidic than acetic acid. Why ?


(c) Write the products formed when (CH3)3C–CHO reacts with the following :


(i) Zinc amalgam and dilute hydrochloric acid


(ii) Concentrated sodium hydroxide solution


(iii) Semicarbazide and a weak acid


 3

Oxidation of CH3-CHO is easier than CH3-COCH3. Why?

 4

Write the IUPAC name of the following compound: