Chemistry Paper 1 Doubts Here... !

[LimeReem]

http://www.xtremepapers.me/CIE/Cambridg ... 8_qp_1.pdf
q15. howw to do it?

 

[gary221]

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_w08_qp_1.pdf
q15. howw to do it?

the ans is A
its becoz d volume of d water has decreased by half
and the temp change is inversely proportional to temp change
so in 1000 cm3 of water temp decreases by 10 c
and so in 500 cm3 temp decreases by 10*2 = 20 c

hope u got it!! :wink:

 

[gary221]

2) B
3) C
4) D
15) (no idea) mayb D
30) D

thnx jim
actually i dont hve d ms 4 this ppr
n i wanted confirmation 4 d ans
m cnfsed bout the 15 one as well

thnx!! :friends: :friends:

 

[xIshtar]

For gary221:

1) B
3) C
4) D
15) D ( I shall explain below)
30) D.

Basically, when heat is liberated it means given out. Burning is an exothermic change right, so heat is liberated, Leaving only C and D. The rate of reaction is then increased by a higher temperature.

 

[gary221]

For gary221:

1) B
3) C
4) D
15) D ( I shall explain below)
30) D.

Basically, when heat is liberated it means given out. Burning is an exothermic change right, so heat is liberated, Leaving only C and D. The rate of reaction is then increased by a higher temperature.

oh so tht was it!!
thnx bro!!! :beer: :beer:

 

[JmCullen]

2) B
3) C
4) D
15) (no idea) mayb D
30) D

thnx jim
actually i dont hve d ms 4 this ppr
n i wanted confirmation 4 d ans
m cnfsed bout the 15 one as well

thnx!! :friends: :friends:

welcome!
btw, i'm not jim.
hahahaha.
jim sounds like boys~
hahaha. 'm girl

oh! so D is right! lucky guess... :beer:

 

[xIshtar]

Not a lucky guess, don't demean yourself.. Call it intiuitive reasoning, sounds much better..

Anyway, I'm open for questions if anyone needs help

 

[JmCullen]

hahaha..
yep! we've to stay optimistic!

 

[anonymous123]

http://www.xtremepapers.me/CIE/Cambridg ... 9_qp_1.pdf
In Q6 it says that the electronic configuration of an ion is 2,8,8 ...I don't understand how is it an ion with a complete outer shell Plz help !!

 

[Keeemoman]

A positive ion such as strontium loses electron to become stable, so according to its group it loses 2 electrons to form from 2.8.8.2 to 2.8.8

 

[gary221]

2) B
3) C
4) D
15) (no idea) mayb D
30) D

thnx jim
actually i dont hve d ms 4 this ppr
n i wanted confirmation 4 d ans
m cnfsed bout the 15 one as well

thnx!! :friends: :friends:

welcome!
btw, i'm not jim.
hahahaha.
oops sorry ma bad!!!
u know wht they say bout d human mind and spelling!!!
jim sounds like boys~
hahaha. 'm girl

oh! so D is right! lucky guess... :beer:

 

[narutogirl]

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_s09_qp_1.pdf
In Q6 it says that the electronic configuration of an ion is 2,8,8 ...I don't understand how is it an ion with a complete outer shell Plz help !!

well..if u look at the periodic table..u will see that sulfur needs to more electrons to become stable it has a valency of 2 that is why it needs to gain 2 more electrons..so it becomes an ion because it fulfilled its wishes and now have a complete outer shell and its ion will be expressed as S^2-

and also with calcium, it needs to lose 2 more electrons to have a complete outer shell so it becomes Ca^2+

now i guess ur question is how did they write 2,8,8 and they don't have full outer shell..its because this its electronic structure "after" losing and gaining

 

[haochen]

 

[JmCullen]

oops sorry ma bad!!!
u know wht they say bout d human mind and spelling!!!

nahh.. it's okayyy

 

[AStarHunter]

guyz, another chemistry doubt in this paper ---> http://www.xtremepapers.me/CIE/inde...GCSE/0620 - Chemistry/&file=0620_s05_qp_1.pdf

The mark scheme says B. Can someone explain why it is D and not B ?

Thnx

 

[xIshtar]

guyz, another chemistry doubt in this paper ---> http://www.xtremepapers.me/CIE/inde...GCSE/0620 - Chemistry/&file=0620_s05_qp_1.pdf

The mark scheme says B. Can someone explain why it is D and not B ?

Thnx

What question dude?

 

[narutogirl]

i have a question how can we sperate sulfur from sand ?

 

[gary221]

i have a question how can we sperate sulfur from sand ?

is it frm a past ppr???
if yes which one??

 

[xIshtar]

i have a question how can we sperate sulfur from sand ?

Hmm, if sand is silicon(iv) oxide, is it not soluble in an organic solvent, as it is a covalent compound? If not, I have no clue, sorry.

 

[gary221]

i have a question how can we sperate sulfur from sand ?

Hmm, if sand is silicon(iv) oxide, is it not soluble in an organic solvent, as it is a covalent compound? If not, I have no clue, sorry.

hey is sulfur soluble in water??