JEE Main 2019 (Online) 9th January Evening Slot | Environmental Chemistry Question 85 | Chemistry

A water sample has ppm level concentration of the following metals : Fe = 0.2; Mn = 5.0; Cu = 3.0; Zn = 5.0. The metal that makes the water sample unsuitable for drinking is :

JEE Main 2018 (Offline)

MCQ (Single Correct Answer)

-1

Out of Syllabus

The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teeth enamel harder by converting
[3Ca₃ (PO₄)₂.Ca(OH)₂] to

[3{Ca(OH)₂}. CaF₂]

[CaF₂]

[3(CaF₂). Ca(OH)₂]

[3Ca₃(PO₄)₂. CaF₂]

JEE Main 2018 (Online) 15th April Evening Slot

MCQ (Single Correct Answer)

-1

Out of Syllabus

Biochemical Oxygen Demand (BOD) value can be a measure of water pollution caused by the organic matter. Which of the following statements is correct ?

Aerobic bacteria decrease the BOD value.

Anaerobic bacteria increase the BOD value.

Clean water has BOD value higher than 10 ppm.

Polluted water has BOD value higher than 10 ppm.

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