The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be \(1000 \mathrm{ppb}, 40 \mathrm{ppb}, 100 \mathrm{ppm}\) and 0.2 ppm , respectively. This water is unsuitable for drinking due to high concentration of :

JEE Main · 2016 · 03 Apr 2016 · Offline · Some Basic Concepts of Chemistry

The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be

1000 ppb, 40 ppb, 100 ppm

and 0.2 ppm , respectively. This water is unsuitable for drinking due to high concentration of :

(A)Lead
(B)Nitrate✓ Correct
(C)Iron
(D)Fluoride

Answer: (B)

Solution

What matters is each level against its own safe limit, not the bare number. Fluoride at 1000 ppb is 1 ppm, near the usual limit of about 1.5 ppm, and lead at 40 ppb sits above its 15 ppb limit but is still a trace. Nitrate, however, is 100 ppm against a permissible limit near 50 ppm, roughly twice what is allowed, making it by far the most seriously raised contaminant and the reason the water is unfit to drink.

JEE Main · 2016 · 03 Apr 2016 · Offline · Single correct option

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JEE Main · 2016 · 03 Apr 2016 · Offline · Some Basic Concepts of Chemistry

Solution

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