i. A piece of magnesium gives of bright flames when burnt.ii. A piece of iron glows red when heated strongly.
The waste from a paper factory contains high amount of hydrochloric acid. How should we treat the waste, before disposal, to make it safe?
Treat it with chemicals containing sodium hydroxide.
Treat it with chemicals containing sulphuric acid
Treat it with chemicals containing sodium chloride
Treat it with pure hydrochloric acid
Which of the following is NOT a chemical change?
Digestion of food
Precipitation of rain and snow
Rusting of iron
Burning of paper
Naturalisation is a
physical change
chemical change
sometimes physical and sometimes chemical change
neither physical nor chemical change
Glowing of an electric bulb is a ________ change.
physical
chemical
both physical and chemical changes
none of these
