Q28 of 30 Page 1

Carbon cannot reduce the oxides of sodium, magnesium and aluminium to their respective metals. Why 2 Where are these, metals placed in the reactivity series? How are these metals obtained from their ores? Take an example to explain the process of extraction along with chemical equations.

The metals high up in the reactivity series are very reactive. They cannot be obtained from their compounds by heating with carbon. For example, carbon cannot reduce the oxides of sodium, magnesium, calcium, aluminium, etc., to the respective metals. This is because these metals have more affinity for oxygen than carbon. These metals are obtained by electrolytic reduction. For example, sodium, magnesium and calcium are obtained by the electrolysis of their molten chlorides. The metals are deposited at the cathode (the negatively charged electrode), whereas, chlorine is liberated at the anode (the positively charged electrode). The reactions are – At cathode Na+ + e–→ Na

At anode 2Cl–→ Cl2 + 2e–



More from this chapter

All 30 →
26

(a) What is the law of dominance of traits? Explain with an example.

(b) Why are the traits acquired during the life time of an individual not inherited? Explain.


 27

(a) A gas is released during photosynthesis. Name the gas and also state the way by which the gas is evolved.

(b) What are stomata? What governs the opening and closing of stomata?


OR


(a) Draw a diagram of human alimentary canal and label – gall bladder, pancreas, liver and small intestine on it.


(b) Give two reasons to explain why absorption of digested food occurs mainly in the small intestine.


 29

The position of certain elements in the Modern Periodic Table are shown below.

Using the above table answer following questions giving reasons in each case :


(i) Which element will form only covalent compounds?


(ii) Which element is a non-metal with valency 2 ?


(iii) Which element is a metal with valency 2 ?


(iv) Out of H, C and F which has largest atomic size?


(v) To which family does H, C and F belong?


OR


Define atomic size. Give its unit of measurement. In the modern periodic table what trend is observed in the atomic radius in a group and a period and why is it so?


 30

(a) Explain with the help of the pattern of magnetic field lines the distribution of magnetic field due to a current carrying a circular loop.

(b) Why is it that the magnetic field of a current carrying coil having


n turns, is 'n' times as large as that produced by a single turn (loop)?