Igcse Model Questions Vol1 2021 Chemistry Question 3
Practice objective / multiple choice question 3 from the 2021 Igcse Model Questions Vol1 Chemistry examination.
A 250 mL water sample is analysed for nitrate (\( \text{NO}_3^- \)) using a colourimetric method. A 25.0 mL aliquot of the sample is diluted to 125.0 mL with distilled water and its absorbance at 540 nm is measured as 0.650. The calibration relationship for the diluted solutions is \( A = 0.020\,C + 0.040 \), where \( C \) is the nitrate concentration in \( \text{mg L}^{-1} \). Calculate the nitrate concentration in the original water sample (in \( \text{mg L}^{-1} \)) and state whether it exceeds the WHO guideline of 50 mg L(^{-1}\).
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This is Igcse Model Questions Vol1 2021 Chemistry Question 3. It is one of the objective questions from the 2021 Igcse Model Questions Vol1 Chemistry examination.
Difficulty level: Hard .
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