Pollution of water originates from human activities. Select the CORRECT points related to water pollution. (1) Clean water would have a BOD value of less than 5 ppm, whereas highly polluted water woul

Question

Pollution of water originates from human activities. Select the CORRECT points related to water pollution.

(1) Clean water would have a BOD value of less than 5 ppm, whereas highly polluted water would have a BOD value of 17 ppm or more.

(2) F⁻ concentration above 2 ppm causes brown mottling of teeth.

(3) The upper limit concentration of lead in drinking water is about 50 ppb.

(4) The maximum limit of nitrate in drinking water is 50 ppm.

(5) Greater than 500 ppm of sulfate in drinking water causes a laxative effect.

(6) 0.2 ppm of Fe and Al and 3 ppm of Cu metal is the maximum prescribed concentration in drinking water.

TestHub · Accepted Answer

All six statements are correct:

Statements (1) & (2): Clean water has a $BO D < 5 pp m$ (polluted $> 17 pp m$ ), and fluoride levels exceeding $2 pp m$ cause brown mottling of teeth.

Statements (3) & (4): The maximum permissible limit for lead in drinking water is exactly $50 pp b$ ( $0.05 pp m$ ), and for nitrate, it is $50 pp m$ .

Statement (5): A sulfate concentration greater than $500 pp m$ is known to cause a harmful laxative effect.

Statement (6): The standard maximum prescribed limits for metals are accurately given as $0.2 pp m$ for $F e$ and $A l$ , and $3 pp m$ for $C u$ .

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