JEE Main levelSingle correct optionDifficulty 2 of 3ev138
Match the standard value (Column I) with the quantity (Column II).
Column I: P = BOD of clean water, Q = BOD of heavily polluted water, R = dissolved oxygen for good growth of fish, S = nitrate limit in drinking water.
Column II: 1 = less than 5 ppm, 2 = more than 17 ppm, 3 = about 6 ppm or more, 4 = 50 ppm.
AP-1, Q-2, R-3, S-4
BP-2, Q-1, R-3, S-4
CP-1, Q-2, R-4, S-3
DP-3, Q-2, R-1, S-4
Answer: A
Clean water has BOD below 5 ppm, and heavily polluted water has BOD above 17 ppm. Fish need dissolved oxygen of about 6 ppm or more, and the nitrate limit is 50 ppm.