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Re: HSC 2015 4U Marathon https://imgur.com/4t4ZTxf The equation x^3 + 3x + 2 has roots A, B and Y. Find the equation with roots A + 1/A, B + 1/B and Y + 1/Y.

re: HSC Chemistry Marathon Archive We would begin to see solid silver (in my example) forming; either as a powder in the solution which falls to the bottom, or it may deposit/accumulate on the solid piece of metal that we insert into the solution in the first place (in my example, the silver...

re: HSC Chemistry Marathon Archive Elements higher in the activity series are more reactive; physically, what this means is that the element is more likely to want to give up its valence electrons. In a salt solution, e.g. AgCl, what is actually present in the solution is Ag+ and Cl- ions: the...

re: HSC Chemistry Marathon Archive Explain why monitoring the reaction vessel used in the Haber process is crucial and describe the monitoring required (6 marks)

Nearly finished FI2I, but I'm about 1/4 of the way through writing notes for FQ2Q

Re: MX2 2015 Integration Marathon Can someone give me an overview of how I should approach 'subbing in infinity' like you do while evaluating this integral? e.g. what to do when there's fractions involved, etc

I still can't get it. I've tried two ways but I can't find how to do it: cosB = DB/2r, then to show our desired result we'd have to show that sinA = EC/DB, which I can't see how to do. or: cosB = EC/DC, then we'd have to prove that sinA = DC/2r, which I can't see how to do. Can somebody spell...

https://imgur.com/lLxdv2l I have been stumped with one simple part in part iii: both of the solutions that I have looked at state: "similarly, CE = 2rcosBsinA" but I can't seem to work out how to actually show this. It's probably something heaps simple that I've overlooked but I'm getting...

re: HSC Chemistry Marathon Archive Natural systems in which biological organisms thrive often require specific, narrow pH ranges in order for the organism(s) to survive; conditions outside of this range will cause harm (e.g. induce acidosis) and often death for organisms. Often in situations...

You certainly wouldn't get marked down for not 'simplifying', however if the resultant number in the log (in this case, 648) isn't too large, then it may make the answer look neater. I don't think that there is any official answer as to which answer is simpler though.

re: HSC Chemistry Marathon Archive Ever since CFCs were phased out in the 80s and 90s by the Montreal Protocol, alternative chemicals have been developed to replace them: hydrofluorocarbons and hydrochlorofluorocarbons. The compounds in the latter group are generally about 10% as dangerous as...

The chemistry concepts introduced in Prelim such as calculations, types of bonding, enthalpy, etc are relevant to HSC Chem, however, most of the non-skills based content is not relevant. As far as I can remember, the only example that breaks this rule is hydrocarbon stuff right at the end of Prelim

re: HSC Physics Marathon Archive Both Max Planck and Albert Einstein, in the early to mid 20th century, had strong views about the role of science in the lead-up to war. Discuss Planck's and Einstein's differing views about whether scientific research is removed from social and political...

re: HSC Physics Marathon Archive Thomson set up a cathode ray tube featuring both a magnetic and electric fields which deflected the cathode rays in opposite directions; by adjusting the strengths of these fields so that they cancelled each other out, he could determine the velocity of the...

re: HSC Chemistry Marathon Archive In industrialised regions, various non-metal oxides such as nitrous oxide and sulfur dioxide are released into the environment as pollution. Specifically, sulfur dioxide can ionise in rain to form sulfurous acid, a constituent of acid rain: SO2 (g) + H2O (l)...

re: HSC Chemistry Marathon Archive By including relevant chemical equations in your answer, justify the procedure you used to prepare an ester in a school laboratory. 6 marks

re: HSC Chemistry Marathon Archive Lavoisier was the first to properly define what an acid is; suggesting that they contained oxygen, however this was flawed as many acids such as HCl do not contain oxygen, and bases such as NaOH. Davy showed that HCl didn't contain oxygen and proposed that...

re: HSC Chemistry Marathon Archive My textbook says that it is soluble in HNO3

Re: MX2 2015 Integration Marathon Not sure if anyone's asked this; it's a fun one which requires the use of complex numbers (at least for my method of working it out): \int \sqrt{\tan{x}}} dx

re: HSC Chemistry Marathon Archive Here's my attempt; keep in mind that I'm fairly new to learning all of the ion tests / solubility rules. i.If we add HNO3, and then add Ba(NO3)2, the precipitate formed by sulfate (BaSO4) is insoluble in HNO3, whereas the phosphate precipitate...