The answer is 2 electrons.
The electron configuration of calcium is 2:8:8:2
Calcium has two electrons in its outermost shell. These are its valence electrons and are the ones used in bonding with other elements. Valence electrons of an atom are those electrons that are in its outer energy shell or that are available for bonding.
Calcium is a metal. When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms forming ions. The resulting compound is known as an ionic compound.
For example, when calcium metal reacts with chlorine gas, calcium gives up its two valence electrons and Chlorine accepts them resulting in a new substance called calcium chloride in which the two elements have ended up forming ionic bonds.
<u>Answer:</u> The standard potential of the cell is 0.77 V
<u>Explanation:</u>
We know that:

The substance having highest positive
reduction potential will always get reduced and will undergo reduction reaction.
The half reaction follows:
<u>Oxidation half reaction:</u> 
<u>Reduction half reaction:</u>
( × 2)
To calculate the
of the reaction, we use the equation:

Substance getting oxidized always act as anode and the one getting reduced always act as cathode.
Putting values in above equation follows:

Hence, the standard potential of the cell is 0.77 V
The top of a wave is called the crest.
Hope I helped! :D
Answer:
Physical change is a temporary change. A chemical change is a permanent change.
Explanation:
A Physical change affects only physical properties i.e. shape, size, etc. Chemical change both physical and chemical properties of the substance including its composition.