Chem Paper 1!

[Adahshan]

http://www.xtremepapers.me/CIE/Cambridg ... 3_qp_1.pdf

Question 8 and 36, I can't understand 36 and 8 i need an explanation for both please!

Thanks.

 

[haochen]

the answer for 8 is C
becoz it doesnt conduct electricity
and they said solid so the melting point should be above 25'C so its C

the answer for 36 is A
becoz it got double bond and alcohol is neutral (u know it from OH)

hope u got it

 

[Adahshan]

Wrong for both. Marking scheme says 36 is A and 8 is C....

What the?

 

[haochen]

really ???? :shock:

 

[Adahshan]

yes....

 

[haochen]

ahhh
i switch both letter !!!!!
my bad
changed them back

hope that doesnt confuse u

 

[Adahshan]

What about.

http://www.xtremepapers.me/CIE/Cambridg ... 4_qp_1.pdf

3
6
11
20
21
27
31

Each of these answers.

 

[LimeReem]

Umm 20 is A
because blue varies from pH 3>14, and pH 3 is acidic!

 

[Outofideaz]

What about.

http://www.xtremepapers.me/CIE/Cambridg ... 4_qp_1.pdf

3
6
11
20
21
27
31

Each of these answers.

3 is A th melting point can not be determined becaz the melting point of NaCl is more than water and is soluble in water
6 is D by looking the periodic table
11 is B i think becaz it produces CO2 which is a heavy gas
20 is A ... the arrows show that clearly since acids have pH less than 7
21 is B since ammonium decomposes producing ammonia by NaOH
27 is C i think since stainless steel is made of nickel chromium and iron
31 is A i think since O2 CO2 is absorbed .. Ar is unreactive and nitrogen just wont react and hydrogen is less reactive than calcium

are these answers correct ... let me know >

 

[JmCullen]

What about.

http://www.xtremepapers.me/CIE/Cambridg ... 4_qp_1.pdf

3
6
11
20
21
27
31

Each of these answers.

3) B, sodium chloride is ionic compound, so it has high m.p. and b.p. therefore it is higher than 100 degree celcius. and since the sodium chloride is place in separate test-tube, it will not dissolve (and it has high m.p. so it will not dissolve as well)

6) D, neon has complete outer most shell. which is 8. and sodium ion, has 8 too. cuz it's ion..

11) A, after heated copper, the product is copper oxide. so, obviously the mass will increase.

20) A, the arrow shows blue in the range of 3-14. pH3 is acid

21) C, the only anion that added metal is nitrate. the metal is aluminum. and nitrate + aluminum + sodium hydroxide = ammonia gas (turns red litmus paper to blue)

27) C, stainless steel include chromium. so, chromium will be added and eventually carbon is remove.

31) D, hydrogen will be absorb by calcium chloride.

hope it helps. and hopefully i didn't explain wrongly..
cheers

 

[Adahshan]

For 11, Why didn't we choose copper (II) oxide?

Also bro, 31, I put because Hydrogen will be absorbed and so left is argon and nitrogen.

 

[Adahshan]

http://www.xtremepapers.me/CIE/Cambridg ... 7_qp_1.pdf

Question 6 Please.

 

[Outofideaz]

can sum1 help me with the questions in the attachment... plz

 

[Outofideaz]

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_s07_qp_1.pdf

Question 6 Please.

B since all the atoms have the same number of electrons in there outer shell , it can be no more than 2 and in period 2 the first element has 3 electrons .. so 2 in the first shell

 

[Adahshan]

You didn't explain why not each choice?

 

[Adahshan]

http://www.xtremepapers.me/CIE/Cambridg ... 7_qp_1.pdf

11
29
Please.

 

[JmCullen]

For 11, Why didn't we choose copper (II) oxide?

Also bro, 31, I put because Hydrogen will be absorbed and so left is argon and nitrogen.

copper oxide?!
after heat, what will it be?
is there something called copper dioxide?
im not sure. hahaha..

31, yes.
hydrogen is absorbed.

 

[xIshtar]

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_w03_qp_1.pdf

Question 8 and 36, I can't understand 36 and 8 i need an explanation for both please!

Thanks.

8 is C.. This is because it needs to be solid at room temperature.

As for 36, it is A. As, unsaturated compounds have a double bond, which eliminates B and D. But because of the OH group, it is soluble in water, and doesn't form a hydroxide..

can sum1 help me with the questions in the attachment... plz

29. I'm sure that it is either C or D.. I would personally go with C, but I'm unsure, sorry.
33. C, as rust forms, thus decreasing the pressure, and causing a sucking effect.
10. Phosphorus is in group 5.. And there are 4 atoms.. So each need to share 3 to gain a full outer shell. Each makes 3 bonds, so they share 2 electrons in each bond, So adding up all bonds: 2+2+2+2+2+2 = 12.
15. I think it is C.. As H+ ions are contained in acids..
39. CH4 + C2H4 + C2H4 = C5H12 => The answer is D.

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_w07_qp_1.pdf

11
29
Please.

For question 11, write out the equation, and attempt to balance it.. And after that, you'll find that it is B..

And for question 29, They are mixtures, and they all conduct electricity as there are metals in it, thus the answer is C.

 

[Adahshan]

http://www.xtremepapers.me/CIE/Cambridg ... 7_qp_1.pdf
Can you get 11 done?

 

[JmCullen]

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_w07_qp_1.pdf

11
29
Please.

11. (im not sure)
29. C, all alloy is a mixture. and they conduct electricity. since alloy contains metal~