firstly, the multimeter actually measures the voltage in this question
and this voltage will increase with the increase in the difference between tendencies for the two metals to form ions (i.e. for the metals to lose electrons)
Therefore, I think u may interpret the question in the following way
So, in Potato A, if the copper and zinc strips are interchanged, the electrons flow from magnesium to copper (instead of from Mg to Zn, which is the original set-up), as copper lose electrons to form ions less readily than zinc. Therefore, the difference between tendencies to form ions is larger, and hence a greater voltage can be produced, thus increasing the multimeter reading.
And for question (e), if the Zn strip is replaced by a Mg strip, there will be no voltage produced as the difference in tendencies for the 2 Mg strips is simply zero. So, the multimeter reading will drop to 0 V.
So, just remember 'voltage will increase with the increase in the difference between tendencies for the two metals to form ions', then I think u can handle this kind of questions well: )
Gayau
