QUESTIONS
1. Give an example of a metal which
(i) is a liquid at room temperature.
Answer
Mercury is an example of metal which is a liquid at room temperature.
(ii) can be easily cut with a knife.
Answer
Lithium, sodium and potassium are the example of metals which can be easily cut with a knife.
(iii) is the best conductor of heat.
Answer
Silver and copper are the metals which are the best conductor of heat.
(iv) is a poor conductor of heat.
Answer
Lead and Mercury are metals which are poor conductor of heat.
2. Explain the meanings of malleable and ductile.
Answer
Malleable is a physical property of metal due to which it is beaten into thin sheet.
Ductile is also a physical property of metal due to which it is drawn into thin wire.
Questions
1. Why is sodium kept immersed in kerosene oil?
Answer
Sodium shows high reactivities towards oxygen. Sodium reacts so vigorously that they catch fire if kept in the open. Hence, to protect it and to prevent accidental fires, sodium is kept immersed in kerosene oil.
2. Write equations for the reactions of
(i) iron with steam
Answer
Iron reacts with steam to form ferric oxide and hydrogen.
Chemical reaction is given below.
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
(ii) calcium and potassium with water
Calcium reacts with water.
Answer
Chemical reaction is given below.
Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)
Potassium reacts with water.
Chemical reaction is given below.
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g) + heat energy
3. Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
Use the Table above to answer the following questions about metals A, B, C and D.
(i) Which is the most reactive metal?
Answer
(ii) What would you observe if B is added to a solution of Copper(II) sulphate?
Answer
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
Answer
4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4.
Answer
5. What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.
Answer
