BAL BHARATI PUBLIC SCHOOL, PITAMPURA, DELHI-110034
CLASS - VIII
Chemistry Core Questions & Answers
Metals & Non-metals
Q1.
Name any four metals and non-metals.
Ans.
Metals - Sodium, Potassium, Magnesium, Copper, Aluminium, Iron and Calcium
Non metals – Oxygen, Nitrogen, Carbon, Chlorine, Sulphur, Phosphorus and
Bromine.
Q2.
Ans.
Define the terms - a. Malleability
b. Lustre
c. Ductility
Malleability : The property of the metal by which they can can be beaten into thin
sheets.
Lustre: Is the shine possessed by elements.
Ductility: The property of metals by which they can be drawn into long and thin
wires.
Q3. How do metals differ from non-metals in their reactivity towards Oxygen ?
Ans: Metals react with Oxygen to form basic oxides except Zinc and Aluminium. Nonmetals react with Oxygen to form acidic or neutral oxides
Q4.
Ans:
Give two examples each of basic Oxides, Acidic oxides, neutral oxides
Basic Oxides: Magnesium oxide and Calcium oxide
Acidic oxides: Carbon di oxide and Sulphur di oxide
Neutral oxide: Carbon Monoxide and Water.
Q5. Why do Copper utensils acquire a dull greenish deposit on them ?
Ans: This is due to corrosion of Copper in presence of moist air leading to formation of
basic Copper Carbonate
Q6.
Define rusting.List the conditions required for rusting. What is the nature of rust.
a. When Iron is exposed to moist air, it develops a reddish brown coating over it
which is called as rust. This phenomenon is known as rusting.
b. There are two conditions for rusting to occur – presence of moisture and
presence of Oxygen.
c. As rust is hydrated Iron oxide, so it is Basic in nature
Q7.
Ans:
a. What happens when Sulphur dioxide is passed in Water ?
b. When iron fillings are added to Sulphuric acid.
c. When Sulphur powder is mixed with Hydrochloric acid.
a. Sulphurous acid is formed.
b. iron reacts with Sulphuric acid to form Iron Sulphate and Hydrogen gas is
released.
c. No reaction takes place as Sulphur is a non metal.
Q8. Name a non-metal which is used in fetilizers
Ans: Nitrogen
Q9. Why does the colour of Copper Sulphate solution change when Zinc is added to it ?
Ans: Zinc is more reactive metal than Copper so it displaces Copper from its salt solution
to form Zinc Sulphate and Copper metal which causes the colour change.
Q10. Why is Phosphorous stored under water while Sodium and Potassium stored under
Kerosene oil.
Ans: Phosphorous is a reactive non metal which reacts with Oxygen but not with water
while Sodium and Potassium react explosively with water and also burn in presence of
Oxygen, hence stored under Kerosene oil.
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