Which of the following elements is used for the vulcanization of rubber?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → S
Natural rubber becomes soft and sticky when warm and brittle when cold. In vulcanisation, raw rubber is heated with sulphur (and an additive) at about 373–415 K. Sulphur forms cross links at the reactive sites of the double bonds, so the rubber becomes stiffer, more elastic and more resistant over a wider range of temperature.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Vulcanisation of Rubber – “… To improve upon these physical properties, a process of vulcanisation is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 K. On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened.”