Question 1

Which of the following statements best explains why the carbonyl group in aldehydes and ketones is polar?

Accepted Answer

The oxygen atom is more electronegative than the carbon atom, creating a partial negative charge on oxygen and a partial positive charge on carbon. 
$$	ext{O} \delta^- \quad 	ext{C} \delta^+$$

Question 2

What is the principal organic product when 1-octanol is treated with potassium dichromate ($$\mathrm{K_2Cr_2O_7}) $$and sulfuric acid ($$\mathrm{H_2SO_4}) $$under mild conditions?

Accepted Answer

Octanal

Question 3

Which of the following alcohols can be oxidized to a ketone using $$\mathrm{K_2Cr_2O_7}$$ and $$\mathrm{H_2SO_4}$$?

Accepted Answer

2-Propanol

Question 4

Why can't tertiary alcohols be oxidized to ketones or aldehydes using potassium dichromate?

Accepted Answer

They lack a hydrogen atom on the carbon bearing the hydroxyl group.

Question 5

Which of the following best describes the product when 2-isopropyl-5-methylcyclohexanol (menthol) is oxidized with $$\mathrm{K_2Cr_2O_7}$$/$$\mathrm{H_2SO_4}$$?

Accepted Answer

A ketone is formed at the position of the original alcohol group.

Question 6

Which reagent is commonly used in the laboratory to reduce aldehydes and ketones to alcohols, but does NOT reduce alkenes?

Accepted Answer

$$\mathrm{$$NaBH_4$$} ($$sodium borohydride)

Question 7

In biological systems, which molecule acts as the reducing agent for the conversion of pyruvate to lactate?

Accepted Answer

NADH

Question 8

Which of the following best describes the structure shown below?

$$\mathrm{CH_3$}$$
$$\quad |$$
$$\mathrm{H-C-OH}$$
$$\quad |$$
$$\mathrm{$$OCH_3$$}$$

Accepted Answer

Hemiacetal

Question 9

Which of the following compounds has the highest boiling point, and why?

Accepted Answer

1-Propanol, because it can form hydrogen bonds.

Question 10

Which of the following statements about keto-enol tautomerism is correct?

Accepted Answer

The keto form is generally more stable than the enol form in aqueous solution.

Question 11

What is the role of a transition metal catalyst (such as Pd or Pt) in the reduction of a carbonyl group with $$\mathrm{H_2$}$$?

Accepted Answer

It activates $$\mathrm{H_2$}$$, allowing it to add to the carbonyl group.

Question 12

Which of the following best describes the change in oxidation state of carbon when a primary alcohol is oxidized to a carboxylic acid?

Accepted Answer

The carbon becomes more oxidized as it forms more bonds to oxygen.

Question 13

Which of the following is true about the formation of cyclic hemiacetals in sugars such as glucose?

Accepted Answer

A hydroxyl group and a carbonyl group within the same molecule react to form a stable ring.

Question 14

Which of the following best describes the effect of increasing ethanol concentration on the equilibrium between an aldehyde, a hemiacetal, and an acetal?

Accepted Answer

The equilibrium shifts toward acetal formation.

Question 15

Which of the following statements about the reduction of ketones is correct?

Accepted Answer

Reduction of a ketone yields a secondary alcohol.

Question 16

Which of the following is the correct balanced equation for the reduction of an aldehyde to a primary alcohol using sodium borohydride ($$\mathrm{$$NaBH_4$$}$$)?

Accepted Answer

$$\mathrm{RCHO + 2[H] \rightarrow RCH_2OH}$$

Question 17

Which of the following best describes the role of NADH in cellular metabolism?

Accepted Answer

It donates a hydride ion ($$\mathrm{H^-}) to $$reduce other molecules.

Question 18

Which of the following is NOT a property of aldehydes and ketones?

Accepted Answer

They can form hydrogen bonds with each other.

Question 19

Which of the following best explains why 1-propanol has a higher boiling point than propanone (acetone)?

Accepted Answer

1-Propanol can form intermolecular hydrogen bonds, while propanone cannot.

Aldehydes and Ketones: Structure, Properties, and Reactions

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