Which of the following is an alloy of copper and tin? MCQ with Answer and Explanation

Explanation:
Starch (polysaccharide) is a natural polymer made from glucose units. It is found in plants. Cellulose, proteins, natural rubber are natural polymers. PVC, nylon, Teflon are synthetic polymers. Natural polymers are biodegradable and renewable. Starch is used as food, in paper, and bioplastics. Synthetic polymers are often derived from petrochemicals.

Explanation:
PVC is a good electrical insulator, resistant to chemicals, water, and fire (self-extinguishing due to chlorine content), making it suitable for cable insulation, pipes, and medical tubing. It is not biodegradable. Flexibility is achieved by adding plasticizers, otherwise rigid. It is an addition polymer of vinyl chloride. Unplasticized PVC (uPVC) is used in construction.

Explanation:
Gypsum (CaSO₄·2H₂O) is added to clinker to slow down the rapid setting of C₃A, providing workable time. Without gypsum, flash set occurs.