Monday, December 17, 2007

Past JEE Questions Ch.13 Non-Metal Elements

JEE question

Statement - 1
Boron always forms covalent bond

Statement - 2

The small size of B^3+favours formation of covalent bond.

(A) Statement – 1 is True, Statement – 2 is True; Statement – 2 is a correct explanation for statement – 1
(B) Statement – 1 is True, Statement – 2 is True; Statement – 2 is Not a correct explanation for Statement – 1.
(C) Statement – 1 is True, Statement – 2 is False
(D) Statement – 1 is False, Statement – 2 is True

answer A
This point is explicitly given in Jauhar's book

JEE Question 2007 Paper I Linked Comprehension

The noble gases have closed-shell electronic configuration and are monoatomic gases under normal conditions. The low boiling points of the lighter noble gases are due to weak dispersion forces between the atoms and the absence of other interatomic interactions. The direct reaction of xenon with fluorine leads to a series of compounds with oxidation numbers +2, +4 and + 6. 4 XeF reacts violently with water to give XeO-3 . The compounds of xenon exhibit rich stereochemistry and their geometries can be deduced considering the total number of electron pairs in
the valence shell.

1. Argon is used in arc welding because of its

(A) low reactivity with metal
(B) ability to lower the melting point of metal
(C) flammability
(D) high calorific value

Solution: A

Argon provides inert atmosphere in welding due to low reactivity with metal.

2. The structure of XeO-3 is

(A) linear
(B) planar
(C) pyramidal
(D) T-shaped

Coorect choice: C

3. XeF-4 and XeF-6 are expected to be

(A) oxidizing
(B) reducing
(C) unreactive
(D) strong basic

Answer: A

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