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Biology; Chemistry; Physics: Post your doubts here!

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explaimn why after hearing a sudden loud noise a persons heart beats faster.
5090/21/M/J/2011
 
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http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_qp_42.pdf

Question 10. Part A
Is the graph supposed to be like this?
5PONsvm.png
The curve is excellent but since the first point starts from 5 cm^3, don't we have to start fromt there and not from (0,14)?
 
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http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_s11_qp_42.pdf
Q6 .. answer's d)
how ? If Q's conc was halved it should lower rate of reaction but if zinc is powdered, it should increase rate of reaction howcome rate is slower as shown on d) ?
No you have a conceptual error. Decreasing the conc. in this case will mean that less products will be formed. HCl is already the limiting reactant, and if we further decrease its conc. it will quickly finish, and less products will be formed
 
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No you have a conceptual error. Decreasing the conc. in this case will mean that less products will be formed. HCl is already the limiting reactant, and if we further decrease its conc. it will quickly finish, and less products will be formed
that's absolutely fine but if you see they've mentioned powdered zinc(Q) instead of zinc peices .. Q should finish earlier than P
 
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