Chemistry Test 291

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Chemistry Test 291

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Weekly Quiz Competition

Question 1
4 / -1

Which of the following statements about standard enthalpy of formation (Δ_fH^∘) is correct?

A
It is the enthalpy change when 1 mole of a compound is formed from its elements in their standard states.

B
It is always positive for exothermic reactions

C
It can be measured directly for all compounds

D
It is zero for all elements in their standard states

Solution
Question 2
4 / -1

If the standard Gibbs energy change (ΔG^∘) for a reaction is 10 kJ/mol at 298 K, what is the value of the equilibrium constant K?

A
e^{−100/(8.314×298)}

B
e^{10/(8.314×298)}

C
e^{−10/(8.314×298)}

D
e^{−10000/(8.314×298)}

Solution
Question 3
4 / -1

For a reaction with ΔG^∘= −25 kJ/mol at 298 K, what can be inferred about the equilibrium constant K?

A
K > 1

B
K < 1

C
K = 1

D
K = 0

Solution
Question 4
4 / -1

A chemist has four bottles, each containing a pure monocarboxylic acid of formula C₈H₁₆O₂. The acids are (i) 2-ethyl-2-methylhexanoic acid, (ii) 2,2,3-trimethylpentanoic acid, (iii) 2,2-dimethyl-3-ethylbutanoic acid, and (iv) 3,3-dimethyl-2-ethylbutanoic acid. She performs two reactions with each acid: (A) decarboxylation with soda-lime at 630 K, and (B) HVZ bromination followed by treatment with aqueous KHCO₃. For which acid will the total mass of the organic product(s) obtained from reaction A equal exactly 0.500 times the mass of the organic product(s) obtained from reaction B when both reactions start with 1.00 g of the acid? (Assume 100 % yield and no loss of material; treat any stereoisomeric mixture as a single species.)

A
Only (i)

B
Only (ii)

C
Only (iii)

D
Only (iv)

Solution
Question 5
4 / -1

Which reaction is used to distinguish primary, secondary, and tertiary amines?

A
Carbylamine reaction

B
Reaction with Hinsberg's reagent

C
Acylation

D
Nitration

Solution

Hinsberg's reagent (benzenesulphonyl chloride) reacts differently with primary, secondary, and tertiary amines, forming products with varying solubility in alkali.
Question 6
4 / -1

The complex [Co(NH₃)₅(NO₂)](NO₃)₂ can exhibit which type of isomerism?

A
Geometrical and optical isomerism

B
Ionization and linkage isomerism

C
Solvate and coordination isomerism

D
Only optical isomerism

Solution
Question 7
4 / -1

Freon-12 (CCl₂F₂) is manufactured from tetrachloromethane via the Swarts reaction. What is the primary industrial use of Freon-12?

A
As a fuel additive

B
As a solvent in organic synthesis

C
As an aerosol propellant and refrigerant

D
As a pesticide

Solution

Freon-12 is widely used in refrigeration, air conditioning, and aerosol propellants due to its stability and ease of liquefaction. It is not used as a fuel additive, solvent, or pesticide.
Question 8
4 / -1

Conductance of 0.1 M KCl (conductivity = X ohm⁻¹cm⁻¹) filled in a conductivity cell is Y ohm⁻¹.
If the conductance of 0.1 M NaOH filled in the same cell is Z ohm⁻¹, the molar conductance of NaOH will be:

A

B

C

D

Solution
Question 9
4 / -1

At 20^∘C, the Ag⁺ ion concentration in a saturated solution of Ag₂CrO₄ is 1.5 × 10⁻⁴ mole/litre.

At 20^∘C, the solubility product of Ag₂CrO₄ would be:

A
3.3750 × 10⁻¹²

B
1.6875 × 10⁻¹⁰

C
1.6875 × 10⁻¹²

D
1.6875 × 10⁻¹¹

Solution
Question 10
4 / -1

The solubility product of AgCl is 1.44 × 10⁻⁴ at 100^oC . The solubility of silver chloride in boiling water may be

A
0.72 × 10⁻⁴ M

B
1.20 × 10⁻² M

C
0.8 M

D
0.5 M

Solution