Free Green Chemistry MCQs with Answers

1. The whiteness of the recycled newspaper is improved by treating it with:

• A. Sodium hydroxide
• B. Per oxides
• C. Super oxides
• D. Normal oxides

Explanation: A is incorrect as sodium hydroxide is not used for whitening of newspapers.B is correct as per oxides are used to whiten old newspapers.The hydrogen peroxide bleaching process results in not only increased brightness, but also in the improvement of paper physical properties. It is now well established that carboxylic acid groups are beneficial for the bonding of pulp fibers in paper and can increase the strength of paperC is incorrect as super oxides are not used to whiten newspapers.D is incorrect as normal oxides are not used to whiten newspapers.

2. Super Phosphate is made by:

• A. The acidulation of phosphate rock
• B. The alkylation of phosphate rock
• C. The alcoholation of phosphate rock
• D. The alkali addition of phosphate rock

Explanation: The correct answer is A: "The acidulation of phosphate rock." Superphosphate is a fertilizer that is commonly used to provide plants with phosphorus, an essential nutrient for plant growth. It is made by treating phosphate rock with sulfuric acid in a process known as acidulation. This process converts the insoluble phosphate in the rock into a more soluble form that can be absorbed by plants.

3. Thermal processing of industrial waste material aims at:

• A. Burning of waste material in pits
• B. Converting the solid waste into useful products by thermal treatment
• C. Energy recovery from organic matter prior to its final disposal
• D. Size reduction and compaction by thermal process

Explanation: The primary function of thermal treatment is to convert the waste to a stable and usable end product. Therefore the answer will be B.

4. Which one is not a nitrogenous fertilizer?

• A. Ammonium nitrate
• B. Triple phosphate
• C. Urea
• D. Nitro phosphate

Explanation: The correct answer is Triple phosphate. It is a phosphate fertilizer, primarily providing phosphorus rather than nitrogen. Ammonium nitrate, Urea, and Nitro phosphate all contain nitrogen, making them nitrogenous fertilizers. While Nitro phosphate is not primarily used as a fertilizer, it still contains nitrogen, which disqualifies it as the correct answer in this context.

5. The amount of methane in biogas is approximately:

• A. 10-30%
• B. 50-90%
• C. 50-75%
• D. 60-75%

Explanation: Biogas is predominantly composed of methane (CH4) and carbon dioxide (CO2). The methane content typically ranges from 50% to 75% by volume. Option C accurately reflects this range. Option A suggests a much lower methane content than is typical, Option B overestimates the possible upper limit, and Option D does not encompass the full typical range, omitting the lower end.

6. The basic principle of green chemistry is/are:

• A. To prevent waste creation
• B. To maximize the atom economy
• C. To create less hazardous synthetic chemical
• D. All of the above

Explanation: The basic principles of green chemistry encompass all the options listed: A. To prevent waste creation - This is a key principle of green chemistry. It aims to minimize or eliminate the generation of waste products in chemical processes. B. To maximize the atom economy - This principle emphasizes using synthetic methods that incorporate as many atoms of the starting materials as possible into the final product, reducing waste. C. To create less hazardous synthetic chemicals - Green chemistry promotes the development and use of chemicals that are less toxic and hazardous to human health and the environment. Therefore, all of these principles (A, B, and C) are correct and collectively represent the fundamental goals of green chemistry. So the correct option is d.