Biology; Chemistry; Physics: Post your doubts here!

[AhsanAfzal]

We've gone through this a couple of times now. The sulphate ion SO2 (2-) is the more stable ion than hydroxide so the sodium displaces the copper to form a bond with the preferred stable sulphate ion.

how to check if it i more stable? By this series? SO2, NO3, Cl,Br, OH?

 

[Saad Mughal]

how to check if it i more stable? By this series? SO2, NO3, Cl,Br, OH?

Yeah.

 

[papajohn]

37 If 1 mole of each alkane is completely burned in oxygen, which will provide 7 moles of products?
A CH4
B C2H6
C C3H8
D C4H10

5070_w12_qp_12.

 

[Saad Mughal]

37 If 1 mole of each alkane is completely burned in oxygen, which will provide 7 moles of products?
A CH4
B C2H6
C C3H8
D C4H10

5070_w12_qp_12.

Use the equation __CO3 + __H2O.
Now, for 7 products, from the options, the only one that fits is C, i.e. 3CO2 + 4H2O from the C3H8.

 

[asma tareen]

how does the amount of carbon in steel affect the strength of steel???
and its brittleness???

 

[Mohammad Mishal]

how does the amount of carbon in steel affect the strength of steel???
and its brittleness???

higher the carbon, the harder the steel...dont know about its brittleness

 

[asma tareen]

higher the carbon, the harder the steel...dont know about its brittleness

thnx

 

[TheFinalFront]

how does the amount of carbon in steel affect the strength of steel???
and its brittleness???

The higher the carbon, the harder the steel but the more brittle it is, too.
Think of it this way, something that is very hard is also very stiff and does not bend easily. If you try to bend it, it will break - like a pencil. But a soft thing - like an eraser - will bend without breaking and is thus less brittle.

 

[farhan141]

-REMOVED-

 

[farhan141]

-REMOVED-

 

[TheFinalFront]

Please don't mislead people. This is the second time you are doing it. Confirm first then answer. Thanks.

More Carbon = More Strong, Less Brittle.

You're the pot calling the kettle black. Stop misleading others, man.
Here's what the syllabus says:

"describe steels as alloys which are a mixture of iron with carbon or other metals and how controlled
use of these additives changes the properties of the iron, e.g. high carbon steels are strong but
brittle whereas low carbon steels are softer and more easily shaped"​

 

[farhan141]

What about June 2003 P1 Q.28.?

 

[TheFinalFront]

What about June 2003 P1 Q.28.?

Ah, I know what's confusing you. If you're using Redspot past papers, they've given the wrong answer. It's A actually. It's given correctly in Classified and my teacher also marked it correct when it came in our test. It's A, not B.

 

[farhan141]

Omg Redspot sucks. The answer ther was B but it is A actually. Sorry Guys.

More Carbon = More Brittle + More Strong,

 

[TheFinalFront]

Omg Redspot sucks. The answer ther was B but it is A actually. Sorry Guys.

More Carbon = More Brittle + More Strong,

It's alright. I was confused the first time as well.

 

[farhan141]

Sorry All. Deep Apologies.

 

[farhan141]

TheFinalFront are there any other wrong answers in RedSpot?

 

[asma tareen]

it wx the sME question which made me come up with this question

 

[farhan141]

it wx the sME question which made me come up with this question

Ok :'(

 

[TheFinalFront]

TheFinalFront are there any other wrong answers in RedSpot?

I regret to say yes. You're best off using the marking scheme. If you have problems with questions before the marking scheme, you can discuss them here. The biggest mistake I've ever seen in Redspot is the question 11 from paper 1 of June 1999. It should be A but they've given it as B. I argued for a whole period with my teacher about it before he understood my point. *facepalm*

 

[farhan141]

Lol. I guess I have to look at marking schemes of all Paper 1 I have done