CIE Chemistry ATP P.42 MCQ query :

[zohra`xo]

color: green, x=7. confirmed.

Can you explain that please?

 

[Haris Sal11]

Urm, guys, x was 7. It's a known value.

 

[Suchal Riaz]

Can you explain that please?

we need full question to solve step by step

 

[Shadow]

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.

Ans was c, n as far as i remember, HCl was used in a n c, while H2SO4 was used in b n d

 

[Haris Sal11]

If 'b' had H2SO4 in it, then by mole ratio, b would be the right answer.

 

[Nouman1997]

If 'b' had H2SO4 in it, then by mole ratio, b would be the right answer.

na bhai c ke ilawa kisi se correct answer nae a raha tha

 

[Bilal Khan]

As far as i know HCl was a and b..

 

[Shadow]

Dont quite remember bout the options, but yea only option c gave exactly double vol of hydrogen

 

[Suchal Riaz]

If 'b' had H2SO4 in it, then by mole ratio, b would be the right answer.

moles of h2so4 were not double than the stated one. i checked them all twice.

 

[Syed Hemail Pasha]

The answer was A ! Just note that H"2"So4 and H"1"cl!.....so the value of 0.004 had to be multiplied by 2

 

[tayyabaaijaz]

I agree the answer was A. student used different acid solution which was hydrochloric acid. and in the question 0.002 moles were prodeuced. and in A 0.004 moles were produced

 

[Shadow]

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

mmm, i dun think thats the comp correct ques

 

[Shadow]

Ok now, ans was C. How? this is how. In the first eq, H2SO4+Mg=MgSO4+H2. Mole ratio between acid and hydrogen gas here is 1:1. So when 0.02 mol of acid was used, o.o2 mol of hydrogen gas was produced. Now the options included HCl as wel, n u had to form the 2nd eq urself. HCl was only given in A n C. New eq was 2HCl+Mg=MgCl2+H2, so mol ratio here between acid and gas is 2:1. In option C, mols of acid came to be 0.08, hence mols of hydrogen were half of this i.e 0.04, which was actually double than the hydrogen produced in the first eq

 

[Haris Sal11]

Answer should be b.

 

[Haris Sal11]

As far as i know HCl was a and b..

Then C can NEVER be the answer.

 

[Shadow]

Then C can NEVER be the answer.

HCl was in A n C - confirm! C was the ans

 

[Nouman1997]

Then C can NEVER be the answer.

and C is still the answer TAALIYAN

 

[Red light]

Guys did we have any question about turning ethanol to ethanoic acid.

 

[Shadow]

Guys did we have any question about turning ethanol to ethanoic acid.

Yea, second ques

 

[Haris Sal11]

HCl was in A n C - confirm! C was the ans

H2SO4 was in b. Number of moles found were 4 x 10(-4). Mole ratio was 1:1. So H2 produced doubled in b.