Question

why does zinc and lead nitrate react?

Answer 1

Zinc is more reactive (Has a lower ionization energy) than Lead. And, the reaction is spontaneous (lead provides the energy for electron transfer plus extra energy). Later you will find out about the concept Gibbs Free Energy and Entropy.

All chemistry is rooted in physics principles. (and some add, physicists each day make those principles up). :)

Answer 2

If the question is about making predictions when a metal is placed in a solution of a salt of another metal, the rule is: <b>a metal (in its elementary form) will replace any other metal in a salt, if the first one is higher than the second on the metal activity series</b>:
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