Biology; Chemistry; Physics: Post your doubts here!

[Saad Mughal]

can you explain the option C

What in it?

 

[usama321]

but this is not the correct answer, mark scheme says Al2O3

well it is a bit tricky. Nitrogen does not directly react with oxygen to form NO2, which is an acidc oxide. Aluminium alone is the answer as aluminium oxide is an amphoteric oxide

 

[asma tareen]

check again its not possible maybe u're looking at the answer of the above part

 

[usama321]

check again its not possible maybe u're looking at the answer of the above part

nitrogen dioxide is formed from nitrogen monoxide

 

[asma tareen]

well it is a bit tricky. Nitrogen does not directly react with oxygen to form NO2, which is an acidc oxide. Aluminium alone is the answer as aluminium oxide is an amphoteric oxide

meuch xaada hee aqal mand hun

 

[asma tareen]

nitrogen dioxide is formed from nitrogen monoxide

exam me bhi bataa dena

 

[Saad Mughal]

meuch xaada hee aqal mand hun

Ye main kya sun rha hun, Zaalimon? usama321

 

[sourov97]

well it is a bit tricky. Nitrogen does not directly react with oxygen to form NO2, which is an acidc oxide. Aluminium alone is the answer as aluminium oxide is an amphoteric oxide

check again its not possible maybe u're looking at the answer of the above part

aluminium oxide is amphoteric...question asks for acidic.
i have checked again....nitrogen is not the ans...wait, amphoteric oxides shows both acidic and basic properties, but that is with water right?

 

[Khadija_1234]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_s07_qp_2.pdf
A8 (b)
Why will there be 2 copper atoms in the Ionic equation?

 

[usama321]

aluminium oxide is amphoteric...question asks for acidic.
i have checked again....nitrogen is not the ans...wait, amphoteric oxides shows both acidic and basic properties, but that is with water right?

not just water, with every other oxides, acids, bases etc so aluminium should be the right answer

Ye main kya sun rha hun, Zaalimon? usama321

masla ye hai ke usne redbull zara zada pee li hai so typing bi galat and baten bi galat

 

[Saad Mughal]

not just water, with every other oxides, acids, bases etc so aluminium should be the right answer

masla ye hai ke usne redbull zara zada pee li hai so typing bi galat and baten bi galat

Oh...

 

[usama321]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s07_qp_2.pdf
A8 (b)
Why will there be 2 copper atoms in the Ionic equation?

it should be Cu + 2H+ = Cu2+ + H2

 

[sourov97]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s07_qp_2.pdf
A8 (b)
Why will there be 2 copper atoms in the Ionic equation?

Cu2+ formed, to balance u need to consider it. (why r u placing 4 before H+, to balance 2H2O)
2Cu + O2 + 4H+ = Cu2+ + 2H2O
hope it helps

 

[Khadija_1234]

it should be Cu + 2H+ = Cu2+ + H2

No it should be Cu + O2 + 4H+ = Cu2+ + 2H2O
But in the mark scheme it's 2Cu + O2 + 4H+ = 2Cu2+ + 2H2O

 

[Khadija_1234]

Cu2+ formed, to balance u need to consider it. (why r u placing 4 before H+, to balance 2H2O)
2Cu + O2 + 4H+ = Cu2+ + 2H2O
hope it helps

Balancing is not done with respect to oxidation state
But thanks

 

[usama321]

it should be Cu + 2H+ = Cu2+ + H2

OOPS, sorry for that i understand now, you have to balance the oxidation numbers too by the way

So, as there Cu + O2 + 4H+ = Cu2+ + 2H2O
In this equation, we have to balance the charges too. There is a charge of 4+ on hydrogen on the left, so the charges must be balanced on the right side. That is why he put a 2 there on the right side. Sorry

 

[sourov97]

Balancing is not done with respect to oxidation state

sorry! i am confused with the mark scheme, accroding to me it should be:
2Cu + O2 + 4H+ = Cu2+ + 2H2O
the qs doesnt say two mol of h2o formed....why did u put 2 befor h2o

 

[usama321]

sorry! i am confused with the mark scheme, accroding to me it should be:
2Cu + O2 + 4H+ = Cu2+ + 2H2O
the qs doesnt say two mol of h2o formed....why did u put 2 befor h2o

you have to balance the charges on both sides too, so you put a 2 before the Cu on the right side, so that the total charge is 4+ like on the left hand side

 

[Khadija_1234]

sorry! i am confused with the mark scheme, accroding to me it should be:
2Cu + O2 + 4H+ = Cu2+ + 2H2O
the qs doesnt say two mol of h2o formed....why did u put 2 befor h2o

Because there was O2 on the left so to balance oxygen on the right we had to put a 2 before H2O and that meant there were 4 hydrogen now so thats why

 

[sourov97]

what about june 06 p2 Q A1 (c)....the answer is Al2O3,,how?