Green Chemistry Questions and Answers

Answer: C

Correct answer: both the assertion and the reason are true and the reason explains the assertion

Both are true and the reason gives exactly the mechanism. Yield measures how much of the theoretical product was obtained and says nothing about how much of the input mass reaches it. A Wittig reaction in quantitative yield still discards nearly three quarters of its mass as phosphine oxide, which is waste however complete the conversion.

Answer: D

Water is indeed safe to handle, but its high latent heat makes it costly to remove and the aqueous effluent may be harder to treat than a recoverable organic solvent. The comparison has to be made for the particular process.

Answer: A

Correct answer: can be computed before the process exists

Atom economy needs only the balanced equation, so competing routes can be compared on paper before any of them is run - which is its whole value at the design stage. The E-factor needs a real process to measure, and it takes account of the solvent and the operating practice that atom economy cannot see.

Answer: B

Correct answer: process mass intensity

Process mass intensity is a green chemistry metric, the total mass of material input per unit mass of product, and it sits alongside atom economy, the E-factor and reaction mass efficiency. The other three are ordinary analytical or materials measurements - of lubricating oil, of refractories and of fats respectively.