Biology; Chemistry; Physics: Post your doubts here!

[Jenn]

How is the answer C?
And how do you find the odd one out in such questions?

View attachment 39853

C because it's the same as the structure shown. As in, it's not branched. It's the same as the structure, the only difference being the CH3 which is rotated. It's just twisted, at the end. It's still a chain.

 

[Awesome12]

C because the third one is the same as the structure shown. As in, it's not branched. It's the same as the structure, the only difference being the CH3 which is rotated. It's just twisted, at the end. It's still a chain.

the question states
Which structure is NOT an isomer

 

[periyasamy]

Hi guys.Can anyone mind explaining this to me .Thanks guys.Cant understand even by refering to books.
Answer is J.
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_43.pdf

 

[Jenn]

the question states
Which structure is NOT an isomer

Exactly. The third one is NOT an isomer. Isomers have different structural arrangement but same formula.
All other options are isomers since they have the same formula but different structures. While the third one is NOT an isomer, since it has the same structural arrangement.

 

[Awesome12]

Exactly. The third one is NOT an isomer. Isomers have different structural arrangement but same formula.
All other options are isomers since they have the same formula but different structures. While the third one is NOT an isomer, since it has the same structural arrangement.

But why isn't it B or D?

 

[Jenn]

But why isn't it B or D?

B and D have a different structure. They are branched. Isomers have to have a branched structure. And all other options are branched. Which means they are isomers.

 

[Awesome12]

B and D have a different structure. They are branched. Isomers have to have a branched structure. And all other options are branched. Which means they are isomers.

Exactly. The third one is NOT an isomer. Isomers have different structural arrangement but same formula.
All other options are isomers since they have the same formula but different structures. While the third one is NOT an isomer, since it has the same structural arrangement.

Oh alright, thanks for the explanation

 

[Faizan Muhammmad]

Of course glass cannot be frozen. It's just a layer of condensed smoke or something on it. This might be for magnification. See page 214 of Federal Physics.

I know I am asking how can light pass if it is smoked or whatever
I will see

 

[Faizan Muhammmad]

Of course glass cannot be frozen. It's just a layer of condensed smoke or something on it. This might be for magnification. See page 214 of Federal Physics.

got it
its to prevent light coming from above to be reflected and interfere with results

 

[asadalam]

But why isn't it B or D?

A better explanation would be that the last CH3 is still attached to the second last CH2 making it pentane-1 or something like that.In the other it is attached to
CH2 in between making it Pentane-2.Get it.The same is with other structures that have functional groups.

 

[funky brat]

How is the answer C?
And how do you find the odd one out in such questions?

View attachment 39853

Actually its'a bit confusing to determine the isomers in condensed structural formula. So make the complete structural formula first showing all bonds. Then see the CH3 group is attached to the first carbon atom. In the first and secondoption, the CH3 group is attached to the second carbon atom, in the last option it's attached to the 3rd carbon atom.

 

[Awesome12]

Another question



Since the no. of moles are changing, won't the enthalphy change also change?

 

[exploded diper]

Another question
View attachment 39864


Since the no. of moles are changing, won't the enthalphy change also change?

in this case the limiting reactant is oxygen... since 1 mole of n2 will react will 2 mole of o2... so if n2 is increaased still the same energy will be released as the o2 is still 1 mole...

 

[Awesome12]

in this case the limiting reactant is oxygen... since 1 mole of n2 will react will 2 mole of o2... so if n2 is increaased still the same energy will be released as the o2 is still 1 mole...

Alright, thanks

 

[exploded diper]

Alright, thanks

haha look at out pics ... they r in the same pose...(but mine is cooler)

 

[kirann]

take a fresh leaf and put it in water ..... bubbles will appear ..showing the presence of stomata

Ik thanks

 

[exploded diper]

Ik thanks

huh

 

[funky brat]

Another question
View attachment 39864


Since the no. of moles are changing, won't the enthalphy change also change?

No, it won't be. Is is limited by the amount of oxygen.

 

[asadalam]

How can we demonstrate presence of stomata in the leaves?

A better experiment would be to attach pieces of cobalt chloride paper to both ends of the leaf.Lower end would change color to pink and indicate presence of stomata

 

[Awesome12]

A better experiment would be to attach pieces of cobalt chloride paper to both ends of the leaf.Lower end would change color to pink and indicate presence of stomata

Isn't that for proving that transpiration occurs most at the bottom of the leaf?