It will received an H+. I’m not sure if that answers your question correctly
Answer: The correct answer is option B.
Explanation: Reactivity of elements is defined as the tendency to loose or gain electrons.
These reactions are a type of single displacement reactions. A single displacement reaction is a type of reaction in which an element displaces another element in a chemical reaction. These are studied with the help of reactivity series.
The element which lies above in the reactivity series can easily displace the element which lies below in the reactivity series.
Option A: This reaction will not yield a stable product because Zinc lies below Aluminium in the reactivity series.

Option B: This reaction will yield a stable product because Sodium lies above Calcium in the reactivity series.

Option C: This reaction will not yield a stable product because Hydrogen lies below Magnesium in the reactivity series.

Option D: This reaction will not yield a stable product because Calcium lies below Barium in the reactivity series.

Option E: This reaction will not yield a stable product because barium lies below Lithium in the reactivity series.

Answer: The correct option is Current W flows at a higher rate than Current Z.
Explanation: To answer this question, we will require Ohm's law.
Ohm's Law states that the current flowing through a conductor across two points is directly proportional to the voltage difference across that two points.
Mathematically,

where, V = voltage
I = Current
R = resistance
For the given question, assuming that the resistance is constant. So, the current is directly proportional to the voltage.

Hence, as the current W is greater of all the given currents so, it will flow at a higher rate.
Therefore, the correct answer is Current W flows at a higher rate than Current Z.