Kerala Board Solutions for Chapter: Chemical Changes, Exercise 7: Let us assess

Identify the energy change involved and write down what type of chemical reaction takes place in glowing of a fire fly.

Identify the energy change involved and write down what type of chemical reaction takes place in plating a copper ring with gold.

Identify the energy change involved and write down what type of chemical reaction takes place in reaction between potassium hydroxide and sulphuric acid.

Identify the energy change involved and write down what type of chemical reaction takes place in Burning of fuels.

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. 

List out the instruments that use electrochemical cells. What are the merits and demerits of using such cells? 

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.

Give an example each for exothermic and endothermic reactions.