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  1. wizzkids

    Can a pencil be used to draw chemical structures?

    Yes! Absolutely. That is why the front cover of the examination paper says, "Draw diagrams using pencil." (and I would add, please use a ruler 👍)
  2. wizzkids

    Free energy and Equilibrium

    Sort answer - Yes, you do. You may be asked questions targetting Module 5, such as 2021 HSC Chemistry Q.33 that use the Gibbs Free energy change. In Year 11 you were introduced to the Gibbs Free Energy change as the driving force for chemical change. In Year 12, you were shown that a system that...
  3. wizzkids

    Can someone explain this?

    A very-well designed AC transformer can be 98 percent efficient. There are three main ways that energy is wasted in AC transformers. (1) electrical resistance in the conductors. (2) magnetic hysteresis in the core material. (3) eddy currents in the magnetic core material. This wasted energy...
  4. wizzkids

    Chemistry Data Analysis vs Chemical Analysis

    Without seeing the notification of the assessment task, I'm guessing that the difference comes down to secondary data versus first-hand data. The HSC Syllabus says that students need to develop both kinds of skills at Stage 6. To analyse secondary sources, you need to identify reliable sources...
  5. wizzkids

    equilibrium constant and temperature

    This topic is never explained properly; I sympathise with your doubts and confusion. Let's start with temperature. What is temperature? Temperature is a measure of the average kinetic energy of particles. The Maxwell-Boltzmann distribution function describes how the kinetic energy of particles...
  6. wizzkids

    Chem question how do u do this?

    There is a so-called "Universal Indicator" that contains a mixture of thymol blue, methyl red, bromothymol blue and phenolphthalein. The aim is to make an indicator that changes colour progressively through the range pH4 to pH14. They supply a colour chart to read off the correct pH value, but...
  7. wizzkids

    Engineering Studies

    Phew ... where to start? In the limited time you have remaining, you must make sure you have revised these topics and have prepared answers to typical questions: (1) AS1100 drawing standards - transforming orthogonal to pictorial, and vice versa. Assembly drawings, sectioned drawings, drawing...
  8. wizzkids

    How much of physics is maths?

    Mathematics Advanced or Mathematics Extension 1 would be quite adequate for HSC Physics. In my experience, you have to distinguish between students who have two types of mathematical ability. There are students who are good at crunching formulae and numbers (which I call formulaic maths) and...
  9. wizzkids

    MCQ help

    Yes, that answer sheet must be wrong. Frequency never changes when a light wave passes between two different mediums. Think of it this way: Crests and troughs are arriving at the interface. (i) If the frequency is going to increase on the other side of the interface, where are these extra crests...
  10. wizzkids

    How much of year 11 physics is important for year 12?

    Short Answer: all of it is important. The more you can retain, the better off you will be. However, some content is definitely more important than others. Vectors, kinematics, dynamics and electromagnetism are absolutely vital. Waves and thermodynamics are less important. After Year 11, you...
  11. wizzkids

    ineq q

    I remember a classic geometric proof of this inequality. I like this proof because it is easy to grasp, and elegant. As a couple of others have said, it is closely related to the arithmetic mean/geometric mean inequality. I also offer a second, more conventional, algebraic proof that relies on...
  12. wizzkids

    2022 Physics QAT MCQ Doubt

    Exam technique. Draw a graph of what you expect the velocity of the skydiver to look like. Transfer any data that is provided onto the graph. Then think about acceleration as the derivative of velocity with respect to time, ie. acceleration is the slope of the velocity versus time graph. Then...
  13. wizzkids

    Radiometric effect

    You are right. All you can conclude is that cathode rays transmit energy, but whether they are particles or waves is impossible to say. Crookes incorrectly attributed the motion of the paddle wheel to momentum transfer from his cathode rays. About 20 years later, J J Thompson (using his new...
  14. wizzkids

    Question

    HSC students will never be required to recall the value of the Hubble Constant Ho (current value 70 kilometres per second per megaparsec). However, students are required to know what it means, and how it was first derived. If any data is required to answer a question related to the Hubble...
  15. wizzkids

    definition of slit width

    Yes, the use of the same symbol "d" can be a bit confusing for students. When we analyse the diffraction pattern produced by a single slit, then d is the symbol given to the width of the slit. As light passes through a single slit, it creates a single bright band accompanied by diffraction...
  16. wizzkids

    Ampere definition limitations

    Rather than re-state the definitions of the fundamental SI units that are readily available on the Internet, I would refer interested students to this article from the United States National Institute of Standards and Technology, about the reason for the change in 2019...
  17. wizzkids

    QAT Help

    The question is examining Module 5 Equilibrium and Acid Reactions, and in particular, solution equilibrium and dynamic equilibrium. The initial solution is saturated, no more solid can dissolve, so IV is wrong. The added mass of the radioactive solid will increase the total solids, so III is...
  18. wizzkids

    Can the fact that magnesium produces a bright light in a flame be used to identify it?

    I think you are referring to combustion of Mg, which gives a very bright white light. No, the white light from burning Mg in oxygen is not a line spectrum. It is a continuous spectrum given off by the hot particles of MgO, which emit a broad continuous spectrum. The characteristic line emission...
  19. wizzkids

    Surfactants

    Surfactant is short for "surface active agent". There are two ways to answer your question. We can cite experimental evidence, or we can give the theory. I will give some evidence. Soaps and detergents concentrate at interfaces as a mono-molecular layer. For example, their presence in the...
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