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NEET Chemistry Solved Question Paper 2009

Multiple Choice Questions

11.

ethylene can be separated from acetylene by passing the mixture through

fuming H₂SO₄
pyrogallol
ammoniacal Cu₂Cl₂
charcoal powder

ammoniacal Cu₂Cl₂

$CH \equiv CH + {Cu}_{2} {Cl}_{2} (ammoniacal) \to \underset{Copper acetylide (red ppt)}{CuC \equiv CCu} {CH}_{2} = {CH}_{2} + {Cu}_{2} {Cl}_{2} (ammoniacal) \to (no reaction) : . Ammoniacal {Cu}_{2} {Cl}_{2} is used to separate ethylene from acetylene .$

12.
If it is assumed that ${}_{92}^{235}U$ decays only by emitting $α$ -and ( $β$ -particles, the possible product of the decay is

${}_{89}^{225}{Ac}$

$_{89}^{227} Ac$

${}_{89}^{230}{Ac}$

${}_{89}^{231}{Ac}$

$_{89}^{227} Ac$

Atomic mass (or mass number) is changed only, when an $α$ -particle is emitted, it is not affected by the emission of $β$ -particle.

${}_{92}^{235}U \overset{- α}{\to} {}_{90}^{231}Y \overset{- α}{\to} {}_{88}^{227}X \overset{- β}{\to} {}_{89}^{227}{Ac}$

13.

The reaction that takes place when Cl₂ gas is passed through conc. NaOH solution is

oxidation
reduction
displacement
disproportionation

disproportionation

When Cl₂ gas is passed through conc NaOH solution, following reaction takes place.

Here, the same element undergoes oxidation and reduction simultaneously, hence it is an example of disproportionation reaction.

14.

Of the following compounds, the most acidic is

As₂O₃
P₂O₅
Sb₂O₃
Bi₂O₃

P₂O₅

Generally, acidic nature of oxides increases along a period from left to right and decreases along a group from up to down.
Since As, P, Sb and Bi all belong to V group and arranged in the following manner :
P: As, Sb, Bi
:. P₂O₅ is the most and Bi₂O₃ is the least acidic.

15.

In the compound $HC \equiv C - C ({CH}_{3}) = {CH}_{2}$ the hybridisation of C-2 and C-3 carbons are respectively

sp³ and sp³
sp² and sp³
sp² and sp
sp³ and sp

sp² and sp

$C_{2} = 3 σ bond \Rightarrow {sp}^{2} hybridisation C_{3} = 2 σ bond \Rightarrow sp hybridisation$

16.

Blackened oil painting can be restored into original form by the action of

Cl₂
BaO₂
H₂O₂
MnO₂

H₂O₂

The lead of oil paintings gets converted into lead sulphide by atmospheric H₂S leading to blackening of paintings. Hydrogen peroxide (H₂O₂) oxidises the black lead sulphide into white lead sulphate, thus restores the colour of oil painting.