15 16 17 18 In 1987, an agreement was formulated by the United Nations Environment Programme (UNEP) to freeze the production of "X" to prevent depletion of "Y". "X" and "Y" respectively referred here are: a) Ozone; CFCs b) CFCs; rays UV c) CFCs; Ozone d) UV rays; Diatomic oxygen Which of the following features relates to biodegradable substances? a) Broken down by biological processes b) Remain inert c) Persist in environment for long time d) May harm the ecosystem Question No. 17 to 20 consist of two statements - Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below: a) Both A and R are true, and R is the correct explanation of A. b) Both A and R are true, and R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true. Assertion: Rusting of Iron is endothermic in nature. Reason: As the reaction is slow, the release of heat is barely evident. Assertion: Probability of survival of an organism produced through sexual reproduction is more than that of organism produced through asexual mode. Reason: Variations provide advantages to individuals for survival.