Additional Questions With Solutions
Q14: Identify following oxides are metallic or non-metallic.
(i) An oxide turns red litmus into blue.
(ii) An oxide turns blue litmus into red.
Ans: (i) Metallic oxide. (ii) Non-metallic oxide.
Q15: Name the metal which reacts vigorously with water.
Ans: Sodium
Q16: Write the name of a non-metal which is a good conductor of electricity.
Ans: Graphite.
Q17: Define displacement reaction with example.
Ans: When a highly reactive metal react with a compound of it replaces the metal from compound such a reaction is called displacement reaction.
Example: CuSO4 + Fe ® FeSO4 + Cu ()
(Here Fe is a highly reactive metal and Cu is a less reactive metal)
Q18: Write three physical properties of metals.
Ans: Three physical properties of metals.
(i) Metals are ductile.
(ii) Metals are malleable.
(iii) Metals are sonorous.
Ques: Write the name of a metal which found liquid at room temperature.
Ans: mercury.
Q19: Name the metals which can be cut with knife.
Ans: Sodium and Potassium.
Q20: What happens when:
(i) Dilute sulphuric acid is poured on a copper plate?
Ans: when sulphuric acid is poured on copper plate copper sulphate is made and hydrogen gas is evolved as per the following chemical equation.
copper plate +sulphuric acid → copper sulphate + hydrogen.
(ii) Iron nails are placed in copper sulphate solution
Ans: When iron nails are placed in copper sulphate solution Cu is displaced by iron and colour of solution changes.
(iii) Write word equations of the reactions involved.
Ans: Chemical eqution is as follows;
Iron nails + sulphate → Iron sulphate + copper.
Q21. Give reasons for the following :
(i) Aluminium foils are used to wrap food items.
Ans: It maintains the temperature of food item intact as it is a good conductor of heat.
(ii) Immersion rods for heating liquids are made up of metallic substances.
Ans: Metals are good conductor of electricity. That is why immersion rods are made up of metals.
(iii) Copper cannot displace zinc from its salt solution.
Ans: It is because copper is less reactive than zinc.
(iv) Sodium and potassium are stored in kerosene.
Ans: It is because sodium and potassium reacts vigorously when come in contact with air or water.
Q22: Why is lemon pickle not stored in an aluminium utensil? Explain.
Ans: As lemon pickle contains acid which highly reactive to aluminium that resulting in destroyed of utensil.
Q23: Write the equation of rusting of iron.
Ans: 3Fe +2H2O + O2 → Fe3O4 + 2H2
Q24: What is the product formed, when sulphur reacts in air (O2)?
Ans: It is sulphur dioxide (SO2).
Q25: What is formed when sulphur dioxide is dissolved in water? Also write the eqution.
Ans: Sulphurous acid is formed.
So2 + H2O → H2SO3 (Sulphurous acid)
Q26: What is the reactivity of non – metals with water?
Ans: Non-metals do not react with water.
