• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Search results

  1. D

    Biology; Chemistry; Physics: Post your doubts here!

    HCL will react with Na2CO3 and not with NaCl. NaOH won't react with either of them.
  2. D

    Biology; Chemistry; Physics: Post your doubts here!

    A) Dibromoethane B) Ethane C) Carbon dioxide and steam D) Ethanol
  3. D

    Biology; Chemistry; Physics: Post your doubts here!

    Hydrogen can reduce lead oxide but not magnesium oxide (re activity series)
  4. D

    Biology; Chemistry; Physics: Post your doubts here!

    Other way around. Losing electrons = Oxidation. Gaining electrons = reduction.
  5. D

    Biology; Chemistry; Physics: Post your doubts here!

    Originally, zinc has a charge of 0. When it forms zinc sulphate, the charge on zinc is +2. Increase in charge means oxidation.
  6. D

    Biology; Chemistry; Physics: Post your doubts here!

    Zinc is more reactive than copper so it will displace copper. The products will be Copper + Zinc Sulphate.
  7. D

    Biology; Chemistry; Physics: Post your doubts here!

    There are 3 marks. 1 for Greent ppt. 1 for saying it's iron hydroxide and the last one for white ppt. Saying the white ppt dissolves is wrong because it doesn't.
  8. D

    Biology; Chemistry; Physics: Post your doubts here!

    mass percentage = (total mr of that element/total mr of compound) * 100
  9. D

    Biology; Chemistry; Physics: Post your doubts here!

    Aluminium has the largest number of valence electrons (3)
  10. D

    Biology; Chemistry; Physics: Post your doubts here!

    Man it lost 2 electrons to form an ion. So electrons will be 2 less than protons.
  11. D

    Biology; Chemistry; Physics: Post your doubts here!

    It will give salt (calcium nitrate) and water like any acid + metal oxide reaction.
  12. D

    Biology; Chemistry; Physics: Post your doubts here!

    It has a +2 charge
  13. D

    Biology; Chemistry; Physics: Post your doubts here!

    Sea water contains water mixed with salts. Air is a mixture of gases.
  14. D

    Biology; Chemistry; Physics: Post your doubts here!

    K+ and H+ won't do anything with NaOH. Fe+2 gives a green ppt and Ca+2 gives white ppt.
  15. D

    Biology; Chemistry; Physics: Post your doubts here!

    Yeah I have the English revision guide which is written by CIE examiners and according to that, they don't deduct marks for not writing the number of words. However, they won't read anything past 160, so you can't score any marks on that.
  16. D

    Biology; Chemistry; Physics: Post your doubts here!

    Too quickly means he added too much (you have to add a few drops if you don't want it to dissolve)
  17. D

    Biology; Chemistry; Physics: Post your doubts here!

    72/18 = 4 moles of water That's 4 moles of H2O, so O is 4 moles.
  18. D

    Biology; Chemistry; Physics: Post your doubts here!

    A precipitate would definitely have been seen if was was Ca+2 because it does not dissolve in excess.
  19. D

    Biology; Chemistry; Physics: Post your doubts here!

    There are 4 moles of water in 72g and 4 moles of O. Mass = Moles * mr = 4 * 16 = 64
  20. D

    Biology; Chemistry; Physics: Post your doubts here!

    http://papers.xtremepapers.com/CIE/Cambridge%20International%20O%20Level/Chemistry%20(5070)/5070_w11_qp_11.pdf Why is the answer to 3 c?
Top