Answers

2016-04-20T18:51:18+05:30
Gold<silver<mercury<copper<lead<tin<iron<zinc<aluminium<magnesium<
calcium<sodium<potassium
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2016-04-20T18:54:51+05:30
The decreasing order of reactivity of some important elements are:

K > Na > Li > Ba > Sr > Ca > Mg > Al > Mn > Zn > Cr >  Fe > Ni > Sn > Pb > [H] > Cu > Hg > Ag > Au > Pt
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