General paper discussion

[asadalam]

Anyway,history paper was really easy!I don't think anyone here would've found it difficult!

 

[Snowysangel]

T

Ans was c. U had to form the second eq as well ... It was lyk dis - 2HCl+(i forgot the other reactant ) = --- + H2 . So mole ratio is 2:1. Whereas eq in the ques was - H2SO4+ (i dont know wat) = --- + H2. Hence mole ratio here is 1:1. So originally there were 0.02 mols of hydrogen gas

There was a second part to the question? X_X

 

[Shadow]

T
There was a second part to the question? X_X

Yea there was, two different acids were involved - HCl n H2SO4

 

[Shadow]

T
There was a second part to the question? X_X

Dont worry, it was just 1 mark

 

[Shadow]

Wat was the ans to that MCQ in which there was a graph? I ticked the option which said - 'the rate of reaction is at its maximum'. Was dis the correct 1?

 

[Snowysangel]

Wat was the ans to that MCQ in which there was a graph? I ticked the option which said - 'the rate of reaction is at its maximum'. Was dis the correct 1?

I marked no more hydrogen is produced

 

[usama321]

I marked no more hydrogen is produced

you are right. This was the answer, cuz the graph had become straight

 

[Shadow]

I marked no more hydrogen is produced

you are right. This was the answer, cuz the graph had become straight

No, if no more hydrogen was produced, the graph would have came down to zero. It was the AMOUNT of hydrogen produced that had became constant

 

[usama321]

No, if no more hydrogen was produced, the graph would have came down to zero. It was the AMOUNT of hydrogen produced that had became constant

k you seem to be confused about reading graphs the y axis was labelled volume of hydrogen. When there is no increase in the y axis, it means there is no hydrogen being produced now. if it had been volume of hydrogen produced, you would have been right

 

[Shadow]

k you seem to be confused about reading graphs the y axis was labelled volume of hydrogen. When there is no increase in the y axis, it means there is no hydrogen being produced now. if it had been volume of hydrogen produced, you would have been right

I don't get it ... y-axis was labelled vol of hydrogen so a horizontal line will represent a constant vol of hydrogen being produced with the passage of time

 

[Suchal Riaz]

it wont be aluminum since aluminum wont react easily either because of the oxide coating. the metal had to be "reactive" and aluminum isn't very reactive therefore it was magnesium, even the Ar confirmed it.

examiner report says any metal between the two stated was accepted. Markscheme mentions even Al3+.
similar question which i dont remember year of.
although i wrote Mg as it's Ar is 24 and charge is 2+.

 

[Suchal Riaz]

View attachment 25441

Anyway,history paper was really easy!I don't think anyone here would've found it difficult!

it is not allowed before 24 hours. XPC bullshit.

 

[usama321]

I don't get it ... y-axis was labelled vol of hydrogen so a horizontal line will represent a constant vol of hydrogen being produced with the passage of time

lets say that at the constant line, the volume of hydrogen was 50cm3. I think it was labelled volume of h2 collected or something like that. When the volume stops increasing, and becomes constant on 50cm3, there is no more h2 being produced

 

[Shadow]

lets say that at the constant line, the volume of hydrogen was 50cm3. I think it was labelled volume of h2 collected or something like that. When the volume stops increasing, and becomes constant on 50cm3, there is no more h2 being produced

ohhh now i get it ... damn it, a mark lost

 

[M.Omar]

View attachment 25441

Anyway,history paper was really easy!I don't think anyone here would've found it difficult!

It went awesome.......alhough they did amend the question about the british control(1750-18500 by the way wht u wrote in that

 

[ijlalm]

lets say that at the constant line, the volume of hydrogen was 50cm3. I think it was labelled volume of h2 collected or something like that. When the volume stops increasing, and becomes constant on 50cm3, there is no more h2 being produced

yeah the vol of H2 became constant..

 

[ijlalm]

Like if you think u would get full marks in physics atp

 

[Snowysangel]

Now that 24 hours have passed, lets discuss the physics atp...what was your value of f? Also how could the problem of the voltage drastically decreasing be avoided (in the last question). And what precautions the student take to make his values of v as accurate as possible?

 

[Asif1223]

Now that 24 hours have passed, lets discuss the physics atp...what was your value of f? Also how could the problem of the voltage drastically decreasing be avoided (in the last question). And what precautions the student take to make his values of v as accurate as possible?

Value of f is 10 cm.
Reverse the polarities of the terminal.
Avoid parallax errors and take more readings

 

[Snowysangel]

I got 9.95 for f, the whole apparatus could be placed outside where there would be a greater availability of sunlight (I have my doubts about it tho). Precautions: avoided parallax error, took the measurement only when a sharp and focused image was formed on the screen (not sure about 2nd point)