Which statement about green chemistry principles in typical chemistry lab experiments is true?

• A. All synthesis performed had over 90% yield.
• B. Use of starting reagents from renewable feedstocks.
• C. Chemicals recycled as part of experimental procedure.
• D. Sunscreen synthesis didn't require heat.

Answer: (C)

Green chemistry emphasizes reducing waste and using resources more efficiently, so recycling chemicals and solvents used in experiments is a direct, practical way to minimize environmental impact. When solvents or reagents are recovered and reused (through distillation, purification, or drying/recycling steps), the lab generates less waste, saves materials, and often improves safety by limiting new chemical purchases and hazardous waste. This practice fits the green chemistry goal of waste prevention and resource conservation, making it the true statement.

The other ideas aren’t universally true in typical lab work: yields can vary and aren’t guaranteed to be very high; not all starting materials come from renewable feedstocks in everyday settings; and many syntheses—including those related to sunscreen compounds—often require heat, so claiming no heating is generally incorrect.