What is the correct sequence, from initial to final, of blue baby disease, methemoglobinemia, in human infants?
1.Conversion of nitrate ions to nitrite ions by microorganisms in human body
2.Oxidation of ions from Fe(II) to Fe(III) in hemoglobin by nitrite ions.
3.Consumption of nitrate polluted water
4.Forming of abnormal hemoglobin called methemoglobin
A3, 2, 1, 4
B3, 1, 2, 4 ✓ Correct
C1, 4, 2, 3
D1, 3, 2, 4
Correct answer: (B) 3, 1, 2, 4
Explanation
The correct order starts with drinking nitrate-polluted water and ends with abnormal haemoglobin forming.
Statement 3, drinking nitrate-polluted water, is the first step.
Statement 1, microbes converting nitrate ions to nitrite ions, comes next.
Statement 2, nitrite oxidising iron from Fe(II) to Fe(III) in haemoglobin, follows.
Statement 4, forming the abnormal methemoglobin, is the final stage.
This methemoglobin cannot carry oxygen well, turning affected infants bluish.
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