$25.$ Which of the following is a primary feedstock for the production of propylene?

a$)$ Methane

b$)$ Butane

c$)$ Ethylene

d$)$ Benzene

$26.$ What is the main function of aromatics in the production of polymers?

a$)$ Providing color

b$)$ Improving mechanical properties

c$)$ Increasing flammability

d$)$ None of the above

$27.$ Which of the following is a common derivative of ethylene?

a$)$ Ethanol

b$)$ Polypropylene

c$)$ Butadiene

d$)$ None of the above

$28.$ What is the primary use of butylene in the petrochemical industry?

a$)$ Production of synthetic rubber

b$)$ Manufacturing of pharmaceuticals

c$)$ Fuel for aviation

d$)$ None of the above