Category : Revision Programme

FRS Chemical Environment

Mr Khemistry

FRS Chemical Environment

FRS Chemical Environment

U and V are structural isomers with molecular formula C7H16.

Both U and V produce the same number of possible structural isomers upon reaction with chlorine to form monochlorinated compounds with the formula C7H15Cl.

Which pairs are possible structures of U and V?

Or

Have a look at the different colour coded hydrogen atoms. Those with the same colour is the same type of hydrogen, i.e. they will form the same product if they are substituted by chlorine. 

Do look out for plane of symmetry as it will greatly accelerate the speed at which you identify FRS Chemical environment.

So answer is 1 and 3 only!

If you’ve enjoyed this organic MCQ, do share it with your friends and see if they are able to do it quickly.

Join us for our weekly tuition classes where we will tackle more of such questions together!

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Organic Chemistry MCQ Analysis

Mr Khemistry

Organic Chemistry MCQ

Organic Chemistry MCQ: Which of the following compounds exhibit cis–trans isomerism?

    1. organic molecule
    2. organic molecule 2
    3. organic molecule 3

Analysis: The question is straightforward. Which compounds exhibit cis-trans isomerism? In the Chemistry H2 syllabus, we learnt about the two criteria for cis-trans isomerism.

  • Presence of C=C bond
  • Different atoms/group of atoms bonded to each of the carbon atoms

Although in the H2 Chemistry syllabus, it is required that C=C bond cannot be in a cyclic structure.

Looking at the three options, looks like none of them can exhibit cis-trans isomerism! But this cannot be the case, let us examine the options carefully.

The three options examined

Option 1: Although there’s no C=C, there is a four-carbon ring structure which restricts rotation. Moreover, the two central carbon atoms each have different atoms bonded to it. So it is able to display cis-trans forms!

Option 2: This is outright wrong as it violates the rule that C=C bond cannot be in a cyclic structure. (But we shall see that the cyclic structure is only limited to 7 carbon ring and below)

Option 3: This is not in the H2 syllabus as cis-trans isomerism can be exhibited by C=C bond in a cyclic structure having more than 7 carbon atoms. Click here to find out more

This Organic Chemistry MCQ isn’t the run-of-the-mill type. Two of the options involves knowledge outside of the H2 syllabus. Most likely, this question is meant to challenge the stronger ability students to read beyond their syllabus requirements. Also, it expose students to a novel context that is slightly outside of their comfort zone.

In our weekly classes, we let students have a chance to try out these challenging questions to stretch them. If you liked doing this question, come join us and broaden your horizon!

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Exam Reduction

Mr Khemistry

Exam Reduction

In a recent article on exam reduction,

Ong Ye Kung

Ong Ye Kung

[…he (Mr Ong YK) also strongly urged tuition centres not to simulate “examination-like conditions” for students to make up for the lost examinations, noting that there are a few who have said they will do so. “Doing so would just be preying on the apprehension and anxieties of parents and students,” he said. “Instead, try to understand why these changes are important to better prepare our young for the future, and help explain this to parents.” “You are going against a very well-thought-out policy which I think has quite good support among students, teachers, and parents,” he told reporters later. “So please work with us.”] 

Source: CNA article

I think the rationale for tests is to assess students’ learning, not “making up for lost exams”. In fact, i think schools will also be continuing un-weighed tests to assess the learning objectives have been met. The key term here is “un-weighed”,  so that it does not add to the students’ stress. For tuition centres whose main objective is improvement of exam grades, it is unlikely to reduce test frequency. We do not speak for other centres, but at Mr Khemistry, we will neither increase nor decrease the number of tests/mock exams. Our main objective is really to let students see how much they understood the contents covered so far and what areas/concepts they might need further strengthening in. Since tuition centres’ tests does not count toward any promotion criteria in school, it will unlikely add a lot of stress to the students. 

An unintentional bottleneck?

In all learning, we need to have milestone/check-point to assess whether we have truly grasped what we have learned. The reason why there’s so many assessments is because we only start to internalize what we learned through practice. The copious amount of content they are supposed to master in the 1.5 years in college is the main reason why frequency of tests/exams is so high.  The main issue is not the rigour of H2 Chemistry (or any other H2 subjects) nor high exam frequency, it is the content quantity. Viewed at a macro level, it’s not difficult to see the bottleneck at JC level. 6 years for foundation at primary school, 4 years for ordinary level at secondary school, 2 years for Advanced level at Junior College, 3-6 years for specialization at University level. 

It’s not difficult to see why Junior College students are stressed out.

What do you think? Leave us a comment!

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June Intensive Revision Programme

Mr Khemistry

J2 students, need some last minute help in Organic Chemistry before your Mid-Year Exams?

Sign up for 4 lessons of intensive revision using 2016 Prelim structured questions from different JCs! Part 1 of our revision program covers the whole spectrum of organic concepts so do come prepared 🙂 Answers will be analysed together and misconceptions will be addressed on the spot.

Dates: 7, 9, 14, 16 June
Time: 2 – 5 pm
Venue: Bukit Timah Shopping Centre unit B2-13C

MCQ and Data-based organic questions will be covered under part 2 of our revision programme.

Dates: 21 and 23 June
Time: 2 – 5 pm
Venue: Bukit Timah Shopping Centre unit B2-13C

J1 students, stressed by your first JC major exam?

Sign up for our J1 revision program covering the core topics, Mole Concept, Gases, Chemical Bonding, Atomic Structure and Redox.

Dates: 5, 12, 19 June
Time: 10 – 1 pm
Venue: Bukit Timah Shopping Centre unit B2-13C

Contact us at enquiry@mrkhemistry.com or SMS/whatsapp us at 98537960 to register for your place today!

ps: Remember to bring along a sweater, it can get cold 🙂

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