Chapter 26, Problem 1SA

Summary Introduction

Introduction:

Hydrogen is a chemical element that is the lightest in the entire periodic table. Oxygen is also an essential element that is vital for the sustenance of life on the earth.

Answer to Problem 1SA

Correct answer:

The main source(s) of hydrogen and oxygen for plants are water and air. Hence, the correct answer is option d.

Explanation of Solution

Reason for correct answer:

Option d. is given as “water and air.”

The nutrients that are required by the plants are mostly found in water and air. The water is a source for hydrogen and oxygen in plants, whereas, air is a source for oxygen. Closure of stomata would hamper the process of photosynthesis which will make plants devoid of food and nutrients. Both water and air are essential sources of hydrogen and oxygen that are required in plants.

Reason for incorrect answer:

Option a. is given as, “soil and air.”

Air is the main source of oxygen for plants, but the soil is neither the main source of oxygen nor hydrogen. Hence, option a. is incorrect.

Option b. is given as, “water and soil.”

The main source of both hydrogen and oxygen for plants is water, but the soil is not a source for both of them. Hence, option b. is incorrect.

Option c. is given as, “water and fertilizer.”

Water is an essential source of both hydrogen and water, but fertilizer is not the main source. Hence, option c. is incorrect.

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

Conclusion

Water and air are the main sources of hydrogen and oxygen for plants. Thus, the correct option is d.