What is change in internal energy when system releases $$8 \mathrm{~kJ}$$ of heat and performs $$660 \mathrm{~J}$$ of work on the surrounding?

Identify the method used to obtain $$\mathrm{SO}_2$$ gas in industry.

Which among the following compounds reacts fastly with $$\mathrm{HBr}$$ ?

Identify biodegradable polymer from following.