Chemistry Test 252

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Chemistry Test 252

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Weekly Quiz Competition

Question 1
4 / -1

Which of the following reactions is an example of a redox reaction?

A
XeF₄ + O₂F₂ → XeF₆ + O₂

B
XeF₂ + PF₅ → [XeF]⁺PF₆^–

C
XeF₆ + H₂O → XeOF₄ + 2HF

D
XeF₆ + 2H₂O → XeO₂F₂ + 4HF

Solution

A redox reaction involves the increase in the oxidation state of one species (oxidation) and a decrease in the oxidation state of another species (reduction).

Xenon undergoes oxidation, while oxygen undergoes reduction.
Question 2
4 / -1

Which of the following tests cannot be used for identifying amino acids?

A
Biuret test

B
Xanthoproteic test

C
Barfoed test

D
Ninhydrin test

Solution

Barfoed's test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of Copper (II) acetate to Copper (I) oxide, which forms a brick-red precipitate Biuret test , Xanthoproteic test , Ninhydrin test are used for identifying Amino Acids
Question 3
4 / -1

Which dicarboxylic acid in presence of a dehydrating agent is least reactive to give an anhydride :

A

B

C

D

Solution

In the fourth reaction, Adipic acid undergoes a dehydration reaction giving a seven-membered cyclic anhydride which is unstable. It further degrades to form cyclopentanone which is stable. Because the seven-membered anhydride formed is unstable, so the reaction is least likely to occur.
Question 4
4 / -1

The major organic compound formed by the reaction of 1,1,1-trichloroethane with silver powder is:

A
2-Butyne

B
2-Butene

C
Acetylene

D
Ethene

Solution
Question 5
4 / -1

The actinoids exhibit more oxidation states in general than the lanthanoids. This is because:

A
The 5f orbitals are more buried than the 4f orbitals.

B
There is a similarity between 4f and 5f orbitals in their angular part of the wave function.

C
The actinoids are more reactive than the lanthanoids.

D
The 5f orbitals extend further from the nucleus than the 4f orbitals.

Solution

In actinoids, the outermost 5f orbitals are away from the nucleus. This makes them similar in energies to 6d and 7s orbitals. Thus, electrons can easily transition between these orbitals, and once they reach the valence orbital they can be ionized, This leads to the variability in oxidation states. In the case of lanthanoids, the outermost 4f orbitals are too close to the nucleus.
Question 6
4 / -1

The artificial sweetener containing chlorine that has the appearance and taste as that of sugar and is stable at cooking temperature is:

A
Aspartame

B
Saccharin

C
Sucralose

D
Alitame

Solution

The artificial sweetener containing chlorine that has the appearance and taste as that of sugar and is stable at cooking temperature is sucralose. Sucralose is derived from sugar through a multi-step patented manufacturing process that selectively substitutes three atoms of chlorine for three hydroxyl groups on the sugar molecule. This change produces a sweetener that has no calories, yet is 600 times sweeter than sucrose. Sucralose tastes like sugar. Its chemical formula is C₁₂H₁₉Cl₃O₈.
Question 7
4 / -1

The inert gas atom in which the total number of d-electrons is equal to the difference in numbers of total p- and s-electrons, is:

A
He

B
Ne

C
Ar

D
Kr

Solution

He, Ne, and Ar do not have any d electrons, while the difference of their s and p electrons is not zero.

The electronic configuration of krypton (atomic number is 36) is: 1s², 2s², 2p⁶, 3s², 3p⁶, 3d¹⁰, 4s², 4p⁶

Total s-electrons are 8 and total p-electrons are 18. Thus, the difference is 10 and total d-electrons are 10 which are equal.
Question 8
4 / -1

Which of the following is a Lewis acid?

A
PH₃

B
NF₃

C
NaH

D
B(CH₃)₃

Solution

In Trimethyl borane there are only 6 electrons in the valence shell of boron. Also it has one empty p-orbital to accommodate a lone pair of electrons.

Hence, it is a Lewis acid.
Question 9
4 / -1

Which of the following oxides is most acidic?

A
MgO

B
SO₂

C
Al₂O₃

D
Na₂O
Solution
- Acidic oxides are formed by non-metals or elements with high electronegativity.
- SO₂ (sulfur dioxide) is a non-metal oxide and dissolves in water to form sulfurous acid (H₂SO₃), making it highly acidic.
- MgO and Na₂O are basic, while Al₂O₃ is amphoteric.
Question 10
4 / -1

The half-life of a first-order reaction is 60 seconds. What is the rate constant k? (Given: ln⁡(2)=0.693)

A
0.012 s⁻¹

B
0.0115 s⁻¹

C
0.005 s⁻¹

D
0.693 s⁻¹

Solution