Q: Which of the following is a correct representation of the photosynthesis reaction?

$$6\,CO_2$ + 6\,H_2O + \text{energy} \xrightarrow{\text{chlorophyll}} C_6H_{12}O_6$ + 6\,O_2$

Question 1

Which of the following best describes the First Law of Thermodynamics?

Accepted Answer

Energy can be neither created nor destroyed, only transformed from one form to another.

Question 2

Which process is an example of an endothermic reaction?

Accepted Answer

Photosynthesis in plants

Question 3

A coal-burning power plant converts the chemical energy in coal into electricity. Which sequence best describes the energy transformations that occur?

Accepted Answer

Chemical energy → Mechanical energy → Electrical energy

Question 4

Which of the following statements about entropy is correct?

Accepted Answer

Entropy is a measure of the dispersal of energy, and increases in all spontaneous processes.

Question 5

Which of the following is a correct balanced equation for the combustion of methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$\mathrm{CH_4$} + 2\,O_2$ \rightarrow CO_2$ + 2\,H_2O$$

Question 6

If burning 1.00 mol of methane releases 803 kJ of energy, how much energy is released when 2.50 mol of methane is burned?

Accepted Answer

$$2007.5\ \mathrm{kJ}$$

Question 7

Which of the following is a major environmental concern associated with the combustion of coal?

Accepted Answer

Release of sulfur dioxide ($$\mathrm{SO_2$}$$), contributing to acid rain

Question 8

Which of the following best explains why gasoline with a higher octane rating is preferred for modern engines?

Accepted Answer

It is less likely to combust prematurely, preventing engine knocking.

Question 9

Which of the following is a renewable energy source that directly converts sunlight into electricity?

Accepted Answer

Photovoltaic cell

Question 10

Which of the following statements about fossil fuels is correct?

Accepted Answer

Fossil fuels are reduced substances that release energy through exothermic oxidation reactions.

Question 11

Which of the following is a correct representation of the photosynthesis reaction?

Accepted Answer

$$6\,CO_2$ + 6\,H_2O + 	ext{energy} \xrightarrow{	ext{chlorophyll}} C_6H_{12}O_6$ + 6\,O_2$

Question 12

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

Color of the reactants

Question 13

Which of the following is a real-world example of an exothermic process?

Accepted Answer

Burning wood in a campfire

Question 14

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

Accepted Answer

It increases the rate of reaction by lowering the activation energy.

Question 15

Which of the following is a disadvantage of using nuclear energy for electricity generation?

Accepted Answer

It requires elaborate and expensive safety precautions and produces radioactive waste.

Question 16

Which of the following is a correct statement about hydrogen as a fuel?

Accepted Answer

Hydrogen fuel cells produce electricity with water as the only exhaust product.

Question 17

A gasoline has an octane rating of 87. What does this mean?

Accepted Answer

It performs like a mixture of 87% isooctane and 13% heptane in resisting knocking.

Question 18

Which of the following is a real-world application of the Second Law of Thermodynamics?

Accepted Answer

Heat flows spontaneously from a hot cup of coffee to the surrounding cooler air.

Question 19

Which of the following is a benefit of using biomass as an energy source?

Accepted Answer

It recycles carbon dioxide through the atmosphere via photosynthesis.

Question 20

Which of the following best explains why solar energy must be concentrated to be useful for most applications?

Accepted Answer

Solar energy is too diffuse in its natural state to provide sufficient power.

Chapter 15: Energy – Chemistry for Changing Times (Introductory Chemistry Study Notes)

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