Subject

Chemistry

Class

NEET Class 12

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NEET Chemistry Solved Question Paper 2016

Multiple Choice Questions

41.
The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45°C. The degree of association of acetic acid in benzene is (Assume acetic acid dimerises in benzene and K_f for benzene = 5.12K kg mol^-1) M_observed of acetic acid = 113.78

94.5%

54.9%

78.2%

100%

94.5%

Weight of acetic acid = 0.2 gm

Weight of benzene = 20.0 gm

Depression in freezing point = $∆ T_{f}$ = 0.45 $°$ C

$∆ T_{f} = \frac{1000 \times K_{f} \times w_{2}}{w_{1} \times M}$

0.45 = $\frac{1000 \times 5.12 \times 0.2}{20 \times M}$

$∴ M_{(observed)}$ = 113.78 (acetic acid)

2CH₃COOH $⇌$ (CH₃COOH)₂

Before association 1 0

After association 1 - $α$ $\frac{α}{2}$ ( $α$ = degree of association)

Molecular weight of nucleic acid = 60

i = $\frac{Normal molecular mass}{Observed molecular mass}$

$∴ \frac{M_{(normal)}}{M_{(observed)}} = 1 - α + \frac{α}{2} or, \frac{60}{113.78} = 1 - α + \frac{α}{2} ∴ α = 0.945 or 94.5 %$

42.

Which of the following can be oxidised by SO₂?

K₂Cr₂O₇
Mg
H₂O
All of these

43.

A conductivity cell has a cell constant of 0.5 cm^-1. This cell when filled with 0.01 M NaCl solution has a resistance of 384 ohms at 25°C. Calculate the equivalent conductance of the given solution.

130.2 $Ω^{- 1}$ cm² (g eq)^-1
137.4 $Ω^{- 1}$ cm² (g eq)^-1
154.6 $Ω^{- 1}$ cm² (g eq)^-1
169.2 $Ω^{- 1}$ cm² (g eq)^-1

44.

Assertion : Co[Hg(SCN)₆] and Hg [Co(SCN)₆] are isomers.

Reason : SCN^- is a stronger ligand as compared to NCS^-.

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false.
If both assertion and reason are false

45.

Assertion : Acetone and aniline shows negative deviations.

Reason : H-bonding between acetone and aniline is stronger than that between acetoneacetone and aniline-aniline.

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false
If both assertion and reason are false.

46.

Assertion : Charcoal is used in separation of noble gases.

Reason : Charcoal has porous structure

If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false
If both assertion and reason are false

47.

Assertion : A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of a little hydrochloric acid, it becomes laevorotatory.

Reason : Sucrose on hydrolysis gives unequal amounts of glucose and fructose. As a result of this, change in sign ofrotation is observed.

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.

48.

Assertion : In electrolysis, the quantity of electricity needed for depositing 1 mole of silver is different from that required for 1 mole of copper.

Reason : The molecular weights of silver and copper are different.

If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false.
If both assertion and reason are false