Brass gets discoloured in air due to the presence of which gas in air

A. Carbon dioxide

B. Hydrogen Sulphide

C. Oxygen

D. Nitrogen

Please do not use chat terms. Example: avoid using "grt" instead of "great".

You can do it
  1. The formula of Plaster of Paris is
  2. Polythene is industrially prepared by the polymerisation of
  3. Which of the following items will be attracted to the north pole of a permanent magnet by a magnet force?
  4. Cell membrane is
  5. The fastest acting enzyme in the biological kingdom is
  6. The marine animal called dugong which is vulnerable to extinction is a/an
  7. According to Daltons atomic theory the smallest particle which can exist independently is
  8. The chemial name of Uria is
  9. The removal of top soil by water or wind is called
  10. Quartz crystals normally used in quartz clocks etc. is chemically
  11. Which of the following parts of the sun is easily visible only during a total solar eclipse?
  12. Lightening cause rainfall because
  13. The speed of light with the rise in the temperature of the medium
  14. Which of the following elements is non-radioactive?
  15. The intencity of Earthquakes is measured on
  16. The most important ore of Aluminium is
  17. Liquefied Petroleum gas (LPG) consists of mainly
  18. Which of the following is most likely to cause a rise in the average temperature of earth's atmosphere…
  19. Which of the following characters is not shown by hydrogen
  20. The major ingredient of leather is
  21. Earth's seasons are caused by which of the following?
  22. The hardest substance available on earth is
  23. The location and energy of an electron in an atom can be specified by
  24. The metal used in storage batteries
  25. Rust is
  26. Permanent hardness of water, due to sulphates of the metal, can be destroyed by the use of
  27. Which of the following elements is obtained from sea weeds ?
  28. Which of the following elements is a metal
  29. Old-written material, which cannot be read easily can be read by
  30. Bromine is