Q: Which of the following is the correct formula for calculating the percent composition of a component in a mixture?

$$\text{Percent} = \frac{\text{part}}{\text{whole}} \times 100$$

Question 1

Which of the following statements best describes an exergonic reaction as shown in the energy diagrams provided?

Accepted Answer

A reaction where the products have lower free energy than the reactants.

Question 2

Given the reaction: $$\mathrm{CH_4$(g) + 2 O_2$(g) \rightarrow CO_2$(g) + 2 H_2O(g) + heat}$$, how many moles of water are produced from the combustion of 8.0 moles of methane in excess oxygen?

Accepted Answer

$$16.0$$ moles

Question 3

Which of the following factors will NOT increase the rate of a chemical reaction?

Accepted Answer

Decreasing the concentration of reactants

Question 4

Which type of reaction is illustrated by the equation: $$\mathrm{2K(s) + 2H_2O(l) \rightarrow 2KOH(aq) + H_2$(g)}$$?

Accepted Answer

Single replacement

Question 5

In the redox reaction $$\mathrm{2Al + 3Br_2 \rightarrow 2AlBr_3}$$, which element is oxidized?

Accepted Answer

Aluminum

Question 6

Which of the following best describes a catalyst in a chemical reaction?

Accepted Answer

It increases the rate of reaction without being consumed.

Question 7

Which of the following is the correct formula for calculating the percent composition of a component in a mixture?

Accepted Answer

$$	ext{Percent} = \frac{	ext{part}}{	ext{whole}} 	imes 100$$

Question 8

Which of the following Fischer projections represents an epimer of D-allose?

Accepted Answer

Image 6

Question 9

Which of the following best describes the reaction shown in the third image (carboxylate + acetate forming a larger molecule and water)?

Accepted Answer

Condensation

Question 10

Which of the following statements about hydration of an alkene is correct?

Accepted Answer

It is an addition reaction that follows Markovnikov’s rule.

Question 11

Which of the following best describes the glycosidic linkage in the disaccharide shown in the last image?

Accepted Answer

α(1→4) glycosidic bond

Question 12

Which of the following is NOT a reducing sugar?

Accepted Answer

Sucrose

Question 13

How many chiral centers are present in the Fischer projection of D-glucose (image 4)?

Accepted Answer

4

Question 14

Which of the following best describes the difference between enantiomers and diastereomers?

Accepted Answer

Enantiomers are non-superimposable mirror images; diastereomers are not mirror images.

Question 15

Which of the following is the correct formula for calculating the number of stereoisomers for a molecule with $$n$$ chiral centers?

Accepted Answer

$$2^n$$

Question 16

Which of the following best describes the role of water in a hydrolysis reaction?

Accepted Answer

Water acts as a reactant and breaks a bond in the substrate.

Question 17

Which of the following statements about the combustion of alkanes is correct?

Accepted Answer

It produces carbon dioxide and water.

Question 18

Which of the following is the correct equation for calculating the change in free energy ($$\Delta G) $$for a reaction?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 19

Which of the following best describes the difference between aldoses and ketoses?

Accepted Answer

Aldoses have an aldehyde group; ketoses have a ketone group.

Question 20

Which of the following is the correct formula for the gas law relating pressure, volume, temperature, and moles?

Accepted Answer

$$PV = nRT$$

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