Question

What is the decreasing order of reactivity of the following metals? $\mathrm{Na},\mathrm{Al},\mathrm{K},\mathrm{Cu},\mathrm{Ag},\mathrm{Fe}$

• A. $\mathrm{Na}>\mathrm{K}>\mathrm{Al}>\mathrm{Cu}>\mathrm{Ag}>\mathrm{Fe}$
• B. $\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Cu}>\mathrm{Fe}>\mathrm{Ag}$
• C. $\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Fe}>\mathrm{Cu}>\mathrm{Ag}$
• D. $\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Fe}>\mathrm{Ag}>\mathrm{Cu}$

Answer 1

The correct option is C

$\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Fe}>\mathrm{Cu}>\mathrm{Ag}$

This can be explained on the basis of reactivity series which gives us idea about the decreasing order of reactivity of metals. The series can be arranged as:

$\mathrm{K}>\mathrm{Na}>\mathrm{Li}>\mathrm{Ba}>\mathrm{Sr}>\mathrm{Ca}>\mathrm{Mg}>\mathrm{Al}>\mathrm{Zn}>\mathrm{Cr}>\mathrm{Fe}>\mathrm{Cd}>\mathrm{Co}>\mathrm{Ni}>\mathrm{Sn}>\mathrm{Pb}>\mathrm{H}>\mathrm{Sb}>\mathrm{Bi}>\mathrm{Cu}>\mathrm{Hg}>\mathrm{Ag}>\mathrm{Au}>\mathrm{Pt}$

Explanation for correct answer

(C) $\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Fe}>\mathrm{Cu}>\mathrm{Ag}$

Thus, we can mention that option C is the correct answer as it follows the reactivity series.

Explanation for incorrect answer

(a) $\mathrm{Na}>\mathrm{K}>\mathrm{Al}>\mathrm{Cu}>\mathrm{Ag}>\mathrm{Fe}$

It is not following reactivity series trend.

(b) $\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Cu}>\mathrm{Fe}>\mathrm{Ag}$

It is not following reactivity series trend.

(d) $\mathrm{K}>\mathrm{Na}>\mathrm{Al}>\mathrm{Fe}>\mathrm{Ag}>\mathrm{Cu}$

This is also not following reactivity series trend.

So, the correct option is (C)