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POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

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help me wid this one.....oct nov 2003 biology p1.q no..32 asap
 

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assalam alaikum wr wb
Plz can anyone answer that question with a reasoning ?
Its definitely B. I did the same question. Iodide anion always gives yellow colour. If you are solving one of the 1990s papers, the mark scheme shows the wrong answer.
 

Maz

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assalam alaikum wr wb
Plz can anyone answer that question with a reasoning ?
It's Potassium iodide(B).If you remember the test for anions, adding lead nitrate to acidified iodides give a yellow ppt.
 
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It's Potassium iodide(B).If you remember the test for anions, adding lead nitrate to acidified iodides give a yellow ppt.
I know it should B. but according to the ms it says C , cool Crystals Said so in the ms . how could the ms get it wrong ? I am sure there is a reasoning behind this ?
 
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I know it should B. but according to the ms it says C , cool Crystals Said so in the ms . how could the ms get it wrong ? I am sure there is a reasoning behind this ?
The mark scheme is not original (not published by CIE). Maybe that's why. No point in scratching your head to justify C. I am 100 % sure that its B.
 
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Please help me with question 21 of the attached PDF.
 

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Please help me with question 21 of the attached PDF.
I think the anser should be D.. this is because the mixture of ammonia and nitrogen will not react or dissolve in water and hence, the gas will remain intact. In other answers, the gas will react with the solution. Eg. A, sodium hydroxide will react with carbon dioxide to form sodium carbonate! Hope I helped..
 
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