In the question given below, the passage consists of six sentences. The first and sixth sentences are given at the beginning. The middle four sentences have been removed and jumbled up. They are labelled as, P, Q, R, and S. Find out the proper order for the four sentences.
S1: Metals are today being replaced by polymers in many applications.
P: Above all, they are cheaper and easier to process, making them a viable alternative to metals.
Q: Polymers are essentially a long chains of hydrocarbon molecules.
R: Today, polymers as strong as metals, have been developed.
S: These have replaced the traditional chromium-plated metallic bumpers in cars.
S6: Many Indian institutes of science and technology run special programmes on polymer science.
The proper sequence should be