SSC CHSL Model Paper 16

SPRQ is correct order of the sentences.
S. These enthusiasts argue that Mars could be a perennial source of materials for us earthlings.
P. But there is no firm evidence of any valuable mineral that can be extracted from Mars and transported to Earth.
R. They are also unrealistic about the cost of transportation that will be involved in interplanetary movement of men and materials.
Q. Worst, nobody has any idea what undesirable microbes or poisonous materials we will be importing from Mars
Statement ‘S’ follows the opening line ‘S1’ as it talks about the newest mission of exploring Mars and its positive impact. The use of ‘but’ in statement ‘P’ indicates a contrast with statement ‘S’, making ‘PS’ a mandatory pair.
Statement ‘R’ starting with the pronoun ‘they’ - refers to the above statements, hence the sequence will be ‘SPR’. Statement ‘Q’ is the concluding statement as it explains the negative effects of exploring Mars. Hence the correct order will be SPRQ.