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  1. R

    im shit at balancinf equations can any1 do this for me/

    1) Octane burns in air to form carbon dioxide and H2O. 2C8H18 (l) + 25O2 (g) ----> 16CO2 (g) + 18H2O (l) 2) Zinc oxide reacts with excess carbon. 2ZnO (s) +C (s) ----> 2Zn (s) + CO2 (g) 3) Sodium hydroxide and magnesium. [ This reaction doesn't occur since sodium is more reactive than...
  2. R

    Question classifications of elements

    No...silicon isn't a diatomic molecule. If you actually mean sulfur, it can exist in many forms (allotropes) as S2, S6, S8, etc, as molecules.
  3. R

    Question classifications of elements

    5. Select the group that contains only molecules. A Water, methane, copper chloride B Hydrogen, sulfur, argon C Ethane, lead, diamond, oxygen D Bromine, fluroine, silicon dioxide, water A is wrong since copper chloride is ionic and hence, does not occur as a molecule. B is correct since all of...
  4. R

    need help with a question

    Mass of aluminium oxide = mass of aluminium + mass of oxygen Therefore since it says that the masses of the metals increase by a certain percentage, it has gained more mass as a result of reacting and combining with oxygen. Since this is just a percentage, you now need to multiply it by the...
  5. R

    need help with a question

    Aluminium: Mass of aluminium oxide = 189% x 5.00 = 9.45 g Mass of oxygen = 9.45 - 5.00 = 4.45 g
  6. R

    a good textbook

    Try using Deconstructing Perspectives by Janne Schill ?
  7. R

    List the valency of all transition metals that donnot have a valency of 2

    https://cornellchem.wikispaces.com/file/view/pg2_periodic_table_ions.pdf
  8. R

    Passivating metals :3

    Metals that form a passivating layer such as zinc and aluminium do not experience complete corrosion since this oxide layer is non-porous. Metals such as iron and sodium would experience complete corrosion since the oxide layer formed is porous and hence the metal is still prone to further corrsion.
  9. R

    T-Formulae, Auxilary Method and General Solutions

    T-method: Basic info: Let tan(X/2) = t. sinX = 2t / 1 + t^2 cosX = 1 - t^2 / 1 + t^2 Example: 3cosX + 4sinX = -1 (0° =< X =< 360°) 1. Simplify where possible (this is an easy question so you won't be able to simplify it much further). 2. Substitute and solve. Sometimes it will be necessary to...
  10. R

    T-Formulae, Auxilary Method and General Solutions

    Example: 3cosX + 4sinX = -1 (0° =< X =< 360°) T-method: 1. Find the appropriate trig expansion (e.g. sin(a+b), sin(a-b), cos(a+b), cos(a-b). For this example, sin(a+b) or cos(a-b) would be appropriate. 2. Equate one of the trig expansions with the current equation, whilst ignoring the RHS...
  11. R

    Need help interpreting syallabus point

    Identify data sources, gather, process and present information from secondary sources to identify areas of current research and use the available evidence to discuss some of the underlying physical principles used in one application of physics related to waves, such as: Global Positioning System...
  12. R

    Recommended Texbooks/Study Guides for Preliminary HSC?

    Re: Where can I get Fitzpatrick book? + 1
  13. R

    Trig Identity Question

    lols k, thx bro - btw latex is annoying to use =(
  14. R

    Trig Identity Question

    LHS = \frac{sinA}{1+cosA}+\frac{1+cosA}{sinA} = \frac{sin^2A+1+2cosA+cos^2A}{(sinA)(1+cosA)} = \frac{(1-cos^2A)+1+2cosA+cos^2A}{(sinA)(1+cosA)} = \frac{2+2cosA}{(sinA)(1+cosA)} = \frac{2(1+cosA)}{(sinA)(1+cosA)} = \frac{2}{sinA} = 2cosecA = RHS
  15. R

    are we behind?

    Maths: Basic Arithmetic and Algebra/Surds, Trigonometry (Identities, Equations, Functions & Graphing, Sine, Cosine, Area, 3D, Sum and Difference, Double and Half angles, t-method, Auxiliary angles), Functions & Relations. does that count as lagging? =S
  16. R

    auto Cad

    Hmm...play around with the program and each of the tools/functions as an introduction and read the help menu and any tutorials for it. Personally, i would use VectorWorks since it's really easy to use and learn.
  17. R

    math

    Let the number of people behind her equal x and the people in front of her equal x+3. no. of people in front + sue + no. of people in front = 16 x+1+x+3 = 16 2x = 16-4 2x = 12 x = 6 People in front = x + 3 = 6 + 3 = 9 Therefore, Sue is 10th in...
  18. R

    engineering

    http://wiki.answers.com/Q/Why_is_concrete_strong_in_compression_and_weak_under_tension I hope this answers it and good luck for your test ! =)
  19. R

    decent maths textbook?

    Excel for Year 10 does help, if you buy the 'Advanced' Book though. Use Spectrum Mathematics Year 10 Advanced and Mathscape 10 Extension but these books aren't cheap like Excel. =)
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