Available Answers

1. 1.

   Tick (√) the correct options:

   1. During a physical change, ____________ substance is formed.
      1. a new 
      2. no new
      3. a big
      4. a small
   2. When copper sulphate solution reacts with iron, the new substance formed is ____________.
      1. sulphur
      2. sulphur dioxide
      3. copper oxide
      4. iron sulphate
2. 2.

   Tick (√) the correct options:

   1. In which of the following processes, a new substance is formed?
      1. melting
      2. sublimation
      3. evaporation
      4. rusting
   2.  in galvanisation, iron objects are coated with ____________ metal.
      1. aluminium
      2. zinc
      3. copper
      4. silver
   3. Temporary and reversible changes are generally ____________ changes.
      1. physical
      2. irreversible
      3. chemical
      4. mechanical
   4. Which of the following is not a chemical change?
      1. formation of curd
      2. spoilage of food
      3. hammering of metal
      4. digestion of food
   5. Magnesium ribbon burns with ____________ light to from white powder.
      1. white
      2. red
      3. blue
      4. green
   6. Which of the following substance will be formed when magnesium ribbon burns in air?
      1. magnesium carbonate
      2. magnesium bicarbonate
      3. magnesium hydroxide
      4. magnesium oxide 
3. 3.

   Fill in the blanks:

   1. A _______________ change takes place during the melting of ice.
   2. We can change water into ice by ______________.
   3. Rusting makes the iron objects ______________.
   4. The process of depositing a layer of zinc metal on iron objects is called ______________.
   5. ________________ are the purest solid form of a substance with a definite geometrical shape. 
4. 4.

   Give two examples of physical changes.
5. 5.

   What happens when magnesium oxide is dissolved in water?
6. 6.

   What is a chemical reaction?