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CIE Chemistry ATP P.42 MCQ query :

Haris Sal11

Haris Sal11

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After the 24 hour period, please somebody confirm it to me whether the answer of that mcq regarding the doubling of Hydrogen produced was 'b' or 'c'. Thanks :)
 
usama321

usama321

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yup i wrote C too......cuz something like .002 mole of zn or mg or whatever it was were required for the first reaction with h2so4.........now making its reaction with HCl

Mg (or Zn dont remember which it was) + 2HCl = MgCl2 + H2

so, now to double the hydrogen, we required .004 mole of Mg, and if .004 mole were required we would double it that is 0.008 mole of HCl, which was C

P.S. most of the values might be incorrect, but i am trying to give the general explaination of the mcq. Hoping i am right :D
 
Mubeen Ali

Mubeen Ali

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Wasn't it d? I can remember d being sulphuric acid, but with four times the volume and half the concentration, meaning twice the number of moles, which would mean twice the amount of hydrogen being produced
 
S

Snowysangel

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It should've been a :S the original equation had 0.02 moles of hcl which produced .01 moles of hydrogen. To produce 0.02 moles of hydrogen, 0.04 moles of hcl was required...I think
 
Suchal Riaz

Suchal Riaz

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FINAL ANSWER: C
the HCL has 1/2 mol of hydrogen, Sulfuric Acid has 1 mol of hydrogen gas.
we need double the moles of previous one. means 4 times the moles of HCL or double the moles of H2SO4. there was no options with moles of H2SO4 double than original one although in 'C' option the moles of HCL were twice. no need of long calculation which most of us did.
I hope i answers the question.
 
S

Snowysangel

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Suchal Riaz said:
FINAL ANSWER: C
the HCL has 1/2 mol of hydrogen, Sulfuric Acid has 1 mol of hydrogen gas.
we need double the moles of previous one. means 4 times the moles of HCL or double the moles of H2SO4. there was no options with moles of H2SO4 double than original one although in 'C' option the moles of HCL were twice. no need of long calculation which most of us did.
I hope i answers the question.
Click to expand...
The question stated that magnesium reacts with 10 cm3 of 0.01 moles of hcl to produce h2. Which of the following would produce double the volume of hydrogen. 1)10 cm3 of 0.02 moles/dm3 of hcl 2)20 cm3 of 0.01 moles/dm3 3)20 cm3 of 0.02 moles/dm3 4)40 cm3 of 0.01 moles/dm3
 
Haris Sal11

Haris Sal11

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Snowysangel said:
The question stated that magnesium reacts with 10 cm3 of 0.01 moles of hcl to produce h2. Which of the following would produce double the volume of hydrogen. 1)10 cm3 of 0.02 moles/dm3 of hcl 2)20 cm3 of 0.01 moles/dm3 3)20 cm3 of 0.02 moles/dm3 4)40 cm3 of 0.01 moles/dm3
Click to expand...

That's not the complete question. You're missing the names of the acid, which is necessary because of the comparison with mole ratio. I need to know which acid was used in part b. I'd know the answer then.
 
sourov97

sourov97

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What was the colour of FeSO4 in the first question?....was it green or white
and what was the value of x ....common answer is 7, 8 or 11...which one was it?
 
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