Available Answers

1. 1.

   Choose the correct answer from the options given below.

   1. Which of the following cycle includes ammonification as a Step?
      1. Oxygen
      2. Nitrogen
      3. Carbon
      4. Water
   2. Which gas is prepared using potassium chlorate or hydrogen peroxide?
      1. Oxygen
      2. Nitrogen
      3. Chlorine
      4. Helium
   3. Which of the following is a decomposition reaction?
      1. Reaction between hydrogen and sulphur
      2. Heating hydrogen
      3. Heating calcium carbonate
      4. Burning magnesium in air
   4. The rate of evaporation depends on
      1. Temperature
      2. Humidity
      3. Movement of air
      4. All of these
   5. Which of the following is used in making fertilizers and explosives?
      1. Nitrogen
      2. Hydrogen
      3. Aluminium
      4. Iron
2. 2.

   Give one word or a phrase for the following statements.

   1. A change that can be reversed by reversing the conditions that brought about the change.
   2. A homogeneous mixture of a metal with another metal or non-metal.
   3. A natural random motion of the particles of a liquid.
   4. A method of separation of a liquid from a soluble component by first converting the liquid into vapour and then condensing the vapour.
   5. The elements or compounds that take part in a chemical reaction.
3. 3.

   Complete the following skeletal chemical equations.

   1. H2 + O2 ------►
   2. Mg + O2
   3. CaCO3 --^heat--►
   4. H2O --^{electric current}--►
   5. Fe + S -------►
4. 4.

   Name the following.

   1. A greenhouse gas
   2. A malleable and ductile element
   3. A catalyst
   4. A manufacturing process for ammonia
   5. A non-metal which has luster
5. 5.

   Match the columns.

   Column A	Column B
   Burning of candle Sodium Manga dioxide Well defined physical properties Acid rain	A catalyst Sulphur dioxide Pure substance Exothermic chemical Change Natrium

6. 6.

   Burning is a chemical change but melting is a physical change. Give a reason.