Chapter 18, Problem 1SQ

An abundance of___________ in Earth’s early atmosphere would have prevented the spontaneous assembly of organic compounds on early Earth.

a. hydrogen

b. methane

c. oxygen

d. nitrogen

Summary Introduction

Introduction:

Organic molecules are molecules found in all the living organisms. These molecules are formed by a combination of carbon atoms arranged in long chains or rings and other atoms such as hydrogen, oxygen, and nitrogen are attached to the carbon atoms. The first organic molecule is believed to have been formed on earth’s surface nearly 4 billion years ago. RNA is believed to be the first organic molecule.

Answer to Problem 1SQ

Correct answer:

An abundance of oxygen in Earth’s early atmosphere would have prevented the spontaneous assembly of organic compounds on early Earth. Hence, the correct answer is option c.

Explanation of Solution

Reason for correct answer:

Option c. is given as “oxygen.”

Oxidation reaction requires the presence of oxygen in its free form. The presence of oxygen would have caused the breakdown of the organic molecules immediately after their formation, but the absence of oxygen would have promoted the formation of organic molecules.

Reason for incorrect answer:

Option a. is given as, “hydrogen.”

Hydrogen was present in abundance, and the reducing environment favored the formation of organic compounds. Hence, option a. is incorrect.

Option b. is given as, “methane.”

Methane was present in abundance in the early atmosphere of the earth and contributed towards the formation of organic molecules. Hence, option b. is incorrect.

Option d. is given as, “nitrogen.”

Nitrogen gas was present in the early atmosphere in its free form, and it was not responsible for oxidation reactions. So it promoted the formation of organic molecules. Hence, option d. is incorrect.

Hence, the options a., b., and d. are incorrect.

Conclusion

Oxygen causes oxidation reaction. The abundance of oxygen in the early atmosphere of the earth would have resulted in the breakdown of the organic molecules. Thus, the correct answer is option c.