Chemistry Test 259

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Chemistry Test 259

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Weekly Quiz Competition

Question 1
4 / -1

For the reaction 2HI(g) ⇌ H₂(g) + I₂( g) The degree of dissociation (α) of HI(g) is related to equilibrium constant, K_pby the expression

A

B

C

D

Solution
Question 2
4 / -1

In graphite, electrons are

A
Localised on every third C-atom

B
Present in anti-bonding orbital

C
Localised on each C-atom

D
Spread out between the structure

Solution

In graphite, each carbon is sp²-hybridized and the single occupied unhybridized porbitals of C-atoms overlap side wise to give π-electron cloud which is delocalized and thus the electrons are spread out between the structure.
Question 3
4 / -1

The half-life of a reaction A → product is increased two times when the concentration of A is double. The order of the reaction is

A
0

B
1

C
2

D
3

Solution

For a zero-order reaction, the half-life is directly proportional to the initial concentration of A. Hence, the reaction is of zero order.
Question 4
4 / -1

The correct order of pseudohalide, polyhalide and interhalogen are

A
BrI⁻₂, OCN⁻, IF₅

B
IF₅, BrI⁻₂, OCN⁻

C
OCN⁻, IF₅, Brl⁻₂

D
OCN⁻, BrI⁻₂, IF₅

Solution

Some complex ions of nitrogen show similarities with halide ions. These are called pseudohalide ions e.g., NCO⁻,CN⁻etc.

Halogen, among themselves, form complex ions which are called polyhalide ions. e.g., I⁻₃,BrI⁻₂ etc.

Similarly, interhalogens are the compounds of halogen in which one halogen is cation and other halogen is anion. E.g., IF₇, ICl₅, BrF₃,IF₅ etc .
Question 5
4 / -1

Oxymercuration-demercuration of CH₃CH = CH₂ produces

A
CH₃CH₂CH₂OH

B
CH₃CH(OH)CH₃

C
CH₃CH(OH)CH₂OH

D
CH₃COCH₃

Solution

In oxymercuration - demercuration, more stable carbocation is formed and water attacks on more substituted carbon. The reaction is as follows:
Question 6
4 / -1

The incorrect statement is:

A
The colour of [CoCl(NH₃)₅]²⁺ is violet as it absorbs the yellow light.

B
The spin only magnetic moments of [Fe(H₂O)₆]²⁺ and [Cr(H₂O)₆]²⁺ are nearly similar.

C
The spin only magnetic moment of [Ni(NH₃)₄(H₂O)₂]²⁺ is 2.83 BM.

D
The gemstone ruby has Cr³⁺ ions occupying the octahedral sites of Al₂O₃.

Solution

(1) [Fe(H₂O)₆]²⁺, Fe²⁺ → 3d⁶ → 4 unpaired electron

[Cr(H₂O)₆]²⁺, Cr²⁺ → 3d⁴ → 4 unpaired electron

(2) [Ni(NH₃)₄(H₂O)₂]²⁺, Ni²⁺ → 3d⁸ → 2 unpaired electron

μ_m = 2.83 B.M

(3) In gemstone, ruby has Cr³⁺ ion occupying the octahedral sites of aluminium oxide (Al₂O₃) normally occupied by Al³⁺ ion.

(4) The complementary color of violet is yellow.
Question 7
4 / -1

Assertion A: Enol form of acetone [CH₃COCH₃] exists in < 0.1% quantity. However, the enol form of acetyl acetone [CH₃COCH₂OCCH₃] exists in approximately 15% quantity.

Reason R: Enol form of acetyl acetone is stabilised by intramolecular hydrogen bonding, which is not possible in enol form of acetone.

A
A is false, but R is true.

B
Both A and R are true and R is the correct explanation of A.

C
Both A and R are true, but R is not the correct explanation of A.

D
A is true, but R is false.

Solution
Question 8
4 / -1

For the reaction given below:

The compound which is not formed as a product in the reaction is a

A
Compound with both alcohol and acid functional groups

B
Dicarboxylic acid

C
Diol

D
Monocarboxylic acid

Solution
Question 9
4 / -1

Which one of the following reactions will not yield propionic acid?

A
CH₃CH₂CH₂Br + Mg, CO₂ dry ether/H₃O⁺

B
CH₃CH₂CCl₃+ OH^-/H₃O⁺

C
CH₃CH₂COCH₃+ Ol^-/H₃O⁺

D
CH₃CH₂CH₃ + KMnO₄(Heat), OH^-/H₃O⁺

Solution

All except option 1 give propionic acid as the product, but option 1 yields butanoic as the product.
Question 10
4 / -1

Two statements are given below:

Statement I: The melting point of monocarboxylic acid with even number of carbon atoms is higher than that of with odd number of carbon atoms acid immediately below and above it in the series.

Statement II: The solubility of monocarboxylic acids in water decreases with increase in molar mass.

A
Both Statement I and Statement II are correct.

B
Both Statement I and Statement II are incorrect.

C
Statement I is correct but Statement II is incorrect.

D
Statement I is incorrect but Statement II is correct.

Solution

Statement I is correct as monocarboxylic acids with even number of carbon atoms show better packing efficiency in solid state. Statement II is also correct as the solubility of carboxylic acids decreases with increase in molar mass