HARD
8th Kerala Board
IMPORTANT
Earn 100

Cell Instrument in which it is used
Dry cell Radios
Cameras
Clocks
Toys
Mercury cell Watches
Calculator
Electronic instruments
Nickel- cadmium cell Rechargeable torches 
Cameras
Lithium ion cell Mobile phone
Laptops
  • What do we do with these types of cells after their use?
  • Which among these cells can be recharged and reused? 
  • Do they cause environmental pollution? 

Important Questions on Chemical Changes

MEDIUM
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 1

Assess the chemical reactions given below and answer the questions.

Calcium carbonate + heat → Calcium oxide + Carbon dioxide 

Calcium oxide + water → Calcium hydroxide + heat 

a) Mention the reactants and products in each case. 

b) Which among these are endothermic? Which one is exothermic? 

EASY
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 1
Identify the energy change involved and write down what type of chemical reaction takes place in burning of a candle.
EASY
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 2
Identify the energy change involved and write down what type of chemical reaction takes place in glowing of a fire fly.
MEDIUM
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 2
Identify the energy change involved and write down what type of chemical reaction takes place in plating a copper ring with gold.
MEDIUM
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 2
Identify the energy change involved and write down what type of chemical reaction takes place in reaction between potassium hydroxide and sulphuric acid.
EASY
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 2
Identify the energy change involved and write down what type of chemical reaction takes place in Burning of fuels.
MEDIUM
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 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. 
MEDIUM
8th Kerala Board
IMPORTANT
Science for Class 8 - Part 1>Chapter 6 - Chemical Changes>Let us assess>Q 4
List out the instruments that use electrochemical cells. What are the merits and demerits of using such cells?