Chemistry

chemistry based questions
DIRECTIONS : Questions based on Chemistry.
46. What are Rubies and Sapphires chemically known as
  A.  silicon dioxide
  B.  aluminium oxide
  C.  lead tetra oxide
  D.  boron nitride
47. Acid rain contains high levels of
  A.  oxalic acid
  B.  acetic acid
  C.  sulphuric and nitric acids
  D.  carbolic acid

48. Talc contains which one of the following ?
  A.  zinc,calcium,oxygen
  B.  calcium,oxygen,tin
  C.  magnesium,silicon,oxygen
  D.  zinc,tin,sulphur
49. Which one of the following substances is made up of only one type of atoms?
  A.  water
  B.  hydrogen
  C.  milk
  D.  air
50. Which one of the following is used as a mordant in dyeing and tanning indusrty?
  A.  Magnesium oxide
  B.  magnesium carbonate
  C.  magnesium chloride
  D.  magnesium sulphate