Referring to an activity series, which of the following combinations of reactants would not produce a successful single-replacement reaction?
a) li + nacl
b) cu + cacl2
c) mg + fecl3
d) ca + alcl3

Cu + CaCl₂ would not produce a successful single replacement reaction.

Explanation:

Activity series is constructed on the basis of tendency of an element to lose or gain electrons.

An element which can reduced other can replace it from the ionic solution.

More the reactivity of the metal more the tendency to replace others.

The tendency is measured in terms of standard reduction potential, lower the reduction potential more the tendency to replace other (a better reducing agetn).

A) Li + NaCl, here Li is a better reducing agent so can replace sodium.

B) Cu + CaCl₂, here Ca is a better reducing agent so copper cannot replace calcium.

C) Mg + FeCl₃, Mg is a better reducing agent so can replace iron.

D) Ca + FeCl₃, Ca Mg is a better reducing agent so can replace iron.

dynamic equilibrium is the answer.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.