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C1 discussing asnwers

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Original post by MMcG2015

I'm not sure, I wrote use a digital thermometer to take a more accurate reading, also to the other question about high pressure, it is correct for cracking.

Few I knew pressure was the right one

Reply 21

1jonam16

Original post by MMcG2015

I'm not sure, I wrote use a digital thermometer to take a more accurate reading, also to the other question about high pressure, it is correct for cracking.

The answer is some sort of insulation or lid, to reduce heat loss. A similar question came up last year.

Reply 22

Teenw123

Original post by 1jonam16

If you normally do it to 3 s.f. it's fine, but in this case the answer was perfectly 20.3. Therefore, they won't knock off a mark. There\s no need to worry for everything

Exam tip 101- If the question uses 4 significant figures, YOU USE 4 SIGNIFICANT FIGURES otherwise you'll only get the mark for working out

Reply 23

plex-

Original post by Teenw123

Exam tip 101- If the question uses 4 significant figures, YOU USE 4 SIGNIFICANT FIGURES otherwise you'll only get the mark for working out

Dude it will not make any difference. Also, 20.30 is not to 4 significant figures, as a 0 in a decimal is not a significant figure (20.30 = 20.3)

Reply 24

Teenw123

Original post by plex-

Dude it will not make any difference. Also, 20.30 is not to 4 significant figures, as a 0 in a decimal is not a significant figure (20.30 = 20.3)

I've given up on life time to commit. You'll finally learn when you get marked down

Reply 25

B_9710

Original post by plex-

Dude it will not make any difference. Also, 20.30 is not to 4 significant figures, as a 0 in a decimal is not a significant figure (20.30 = 20.3)

If the question said to give an answer to 4sf and you put 20.3 you will definitely be marked down but only 1 mark.

Reply 26

Teenw123

Original post by plex-

Dude it will not make any difference. Also, 20.30 is not to 4 significant figures, as a 0 in a decimal is not a significant figure (20.30 = 20.3)

Example- In one of my recent Physics mocks the answer to a question was 12. However I dropped a mark as I should have written 12.0 as the question used 3 significant figures

Reply 27

MMcG2015

Original post by Teenw123

Few I knew pressure was the right one

I do an Access to Science course in chem and bio alongside my GCSE's (I'm 26 and had no qualifications, so basically had to start again for my uni course in September) and in one of my chem units we went right into cracking and it's definitely right to say pressure. High temperatures and pressures without a catalyst or lower temperatures and pressure with a catalyst.

Reply 28

B_9710

There are 2 types of cracking, thermal and catalytic. One is high temp, high pressure. The other is still high temp (just not as high) and a catalyst (zeolite although others can probably be used). Either of the 2 should probably get full makes although to thermal cracking usually makes aliphatic/ and straight chain compounds (and alkenes).

(edited 7 years ago)

Reply 29

plex-

Original post by B_9710

If the question said to give an answer to 4sf and you put 20.3 you will definitely be marked down but only 1 mark.

It didn't say that in the question though.

Reply 30

Teenw123

Original post by plex-

It didn't say that in the question though.

The other answers were to 4sf so your should have been to 4 as well

Reply 31

plex-

Original post by Teenw123

The other answers were to 4sf so your should have been to 4 as well

The question did not ask you to give your answer to 4 significant figures. M1 for workings (24.36 / 1.2) M2 for correct answer (20.3)

Reply 32

Teenw123

Original post by plex-

The question did not ask you to give your answer to 4 significant figures. M1 for workings (24.36 / 1.2) M2 for correct answer (20.3)

The calculation is there to trick you into believing that 20.3 alone was the right answer, on your own you're supposed to know that it's meant to be 4sf

Reply 33

B_9710

Original post by Teenw123

The calculation is there to trick you into believing that 20.3 alone was the right answer, on your own you're supposed to know that it's meant to be 4sf

What did the question say? If it did not specifically state how many sf then how do you know it should be 4?

Reply 34

KiranSingh_

You will not get marked down because you did not do it to 4sf. There is nothing wrong with 20.3.. If it said give it to 4sf then that was the correct thing to do. However it didn't. 20.3 or 20.30, same thing, still will get the marks.

Reply 35

1jonam16

Original post by Teenw123

The calculation is there to trick you into believing that 20.3 alone was the right answer, on your own you're supposed to know that it's meant to be 4sf

Oh dear, this is chemistry not physics and more often than not, 3 s.f. is fine. You're making a fuss and gaining satisfaction from other people's supposed misfortunes for nothing. If we lose a mark, we lose a mark, though I doubt so.

Reply 36

Dj3824

That maths question was more P1 stuff lol and I put 20.3. Don' remember the question saying round to 4 sig. figures.

RULE OF THUMB FOR EXAMS: Only answer what the question tells you. Even in maths they would tell you to round to a specific amount of sig. figures or decimal places. this is c1 and that wasn't in the syllabus so losing a mark for that would be a pisstake.