Page 90 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

2. Some chemical reactions are given below. Identify the energy
change involved and write down what type of chemical
reaction takes place here.
a) Burning of a candle

b) Glowing of a fire fly
c) Plating a copper ring with gold
d) Reaction between potassium hydroxide and sulphuric
acid

e) Burning of fuels
3. A student tries to plate an iron nail with copper. Draw its
arrangement by selecting the required materials from the list
given below.

Silver nitrate, iron nail, copper sulphate, silver rod, copper
rod, silver plate, iron sulphate, battery, wire, water, beaker.
4. List out the instruments that use electrochemical cells. What
are the merits and demerits of using such cells?
5. Classify the following into physical changes and chemical
changes.
1. Melting of ice.

2. Heating magnesium in water.
3. Silver bromide kept exposed to sunlight.

4. Change happening to soda water on opening its bottle.
6. Give an example each for exothermic and endothermic
reactions.

Extended activities

1. Making a volcano
Heap up some ammonium dichromate powder on a tile.
Deposit on it the chemical present on a match stick, and ignite.
Write down the changes happening there.

Change in colour : .................................................
Change in amount : .................................................
Exchange of energy : .................................................

Basic Science VIII 89