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Chemistry: Post your doubts here!
This looks familar, I believed I might have explained it in one of the videos. Maybe you could check the year of paper and see if it was indeed one of those I upload. -
Chemistry: Post your doubts here!
s10qp12 Q35. X could be NO or SO2. NO + 1/2O2 --> NO2 SO2 + 1/2 O2 --> SO2 Based on examiners report, they don't view CO reacting with O2 as natural reaction with atmosphere, instead it requires burning. Q39. Hmm Q39, it depends if you are able to draw out the structure and use the rules of... -
Chemistry: Post your doubts here!
w07pq1 Q4. There is a significant increased in IE from removing the 2nd to the 3rd electron, means the atom has two outer electrons. Q30. From CH3CH2CH2CO2CH3, the acid produced upon hydrolysis is CH3CH2CH2COOH . Chemical formula is C4H8O2, empirical formula (simplest ratio) C2H4O Q33... -
Chemistry: Post your doubts here!
w11qp12 Q13. C burning in excess O2 forms CO2 S burning in excess O2 forms SO2, some amounts of SO3 might be formed, but would be a minor product compared to SO2. H burning in excess O2 forms H2O s12q12 Q14 CaCO3--> CaO + CO2 (Thermal decomposition, takes in energy, endothermic) CaO + H2O -->... -
Chemistry: Post your doubts here!
For this paper, you can try the video explanations I made, if still unclear, feel free to clarify here. -
Chemistry: Post your doubts here!
s07qp1 Q26. I keep reworking the question as I kept getting C as the answer. I think you typed the answer wrongly. :confused: You need a tertiary alcohol (not oxidised easily) For the alcohol to be chiral, smallest number of carbons for the 3 R groups would be 1,2 and 3 respectively. So... -
Chemistry: Post your doubts here!
Q7. Focus on individual gases first. Helium exerted 12kPa of pressure when occupying 5dm^3 at start, what pressure did it exert when it occupies 15 dm^3 at the end? Pressure (start) x volume (start) = pressure (end) x volume (end) 12 x 5 = pressure (end) x 15 pressure (end) = 4 kPa from helium... -
Chemistry: Post your doubts here!
s08qp1 Q7. Have to read the question carefully, its asking for forces between atoms. This is same question as Q6 of 2013 P12, I can't seem to embed. You can check it online if interested. Q10. Heat of reaction = heat of formation of products - heat of formation of reactions = 2(-110) -(-940)... -
Chemistry: Post your doubts here!
w11qp12 35. Under the high temperatures, Ba(NO3)2 decomposes to BaO (refer to group II nitrates decomposition). Mg reacts with oxygen in the air to form MgO. s12aq12 complex is formed (not sure if in your syllabus) Ag+ (aq) + 2NH3 (aq)--> [Ag(NH3)2]+ (aq) 1. Dative bond between Ag+ ion and... -
Chemistry: Post your doubts here!
Hi there, please include the answers next time to make it easier for us to reply. s10qp12 Q2. A. 1s2 2s2 2p1 ( 1 unpaired e in p orbital) B. 1s2 2s2 2p6 3s2 3p1 ( 1 unpaired e in p orbital) C. 1s2 2s2 2p6 3s2 3p3 (3 unpaired e in p orbital) D. 1s2 2s2 2p6 3s2 3p6 3d1 4s2 (1 unpaired e in d... -
Chemistry: Post your doubts here!
Please include the answers to make it easier for us to reply. :) w11qp12 Q18. Old lime mortar produces a gas when reacted with HCl, so it should be CaCO3 (to produce CO2) , instead of CaO and Ca(OH)2. This leaves us with Options A and D. A: CaO is harder than CaCO3 D: Ca(OH)2 is softer than... -
Chemistry: Post your doubts here!
Hi there, please include the answers next time so its easier for us to reply. Q6. The heat of reaction in the equation is to break 6 N-F bonds, so to get the bond energy, we divide it by 6. Q15. This is an often set question. Group II nitrates decompose based on the equation below: 2... -
Chemistry: Post your doubts here!
w12qp12 Q11. This question does seem a bit confusing at the start. We rely on the definition of bond energy as much as possible to make our choices easier. Bond energy is the energy required to break 1 mole of covalent bonds (with the species in gaseous phase) Notice that option A is purely a... -
Chemistry: Post your doubts here!
Image copied from the internet If temperatures are too low, majority of particles will not have sufficient energy to overcome the Ea (even though its already lowered by a catalyst). This is not limited to just the contact process. -
Chemistry: Post your doubts here!
What year is this from? So I can label my replies for easier search next time. Q26. W: reacts with Br2 and uv to form intermediate CH3CHBrCH3 , which then reacts with CN- X: reacts with Br2 and uv to form intermediate (CH3)2C(OH)Br ,which then reacts with CN- Y: reacts with HBr to form... -
Chemistry: Post your doubts here!
Because 1 mole of Al2C3 has 3 moles of C. So 0.0016 moles of Al2C3 has 0.0016 x 3 moles of C. -
Chemistry: Post your doubts here!
Just uploaded Nov 2013 P11 http://www.youtube.com/playlist?list=PL4Jmce8VJnNU4YaGfNrPYv7SBJXnB1IAC June 2009 P1 (mistakenly typed as 2007 originally) http://www.youtube.com/playlist?list=PL4Jmce8VJnNVom2AGZXz6fdxSnIl9G-8D For those who messaged me to ask, I'ld like to clarify that I did not... -
Chemistry: Post your doubts here!
Please check #9659 on page 583 -
YouTube Videos on Past Year Chemistry MCQs
Nov 2013 P11 http://www.youtube.com/playlist?list=PL4Jmce8VJnNU4YaGfNrPYv7SBJXnB1IAC June 2009 P1 uploaded (mistakenly typed as 2007 originally) http://www.youtube.com/playlist?list=PL4Jmce8VJnNVom2AGZXz6fdxSnIl9G-8D For those who messaged me to ask, I'ld like to clarify that I did not do... -
YouTube Videos on Past Year Chemistry MCQs
not too sure I understand. What do you mean?