Answer: A chemical equilibrium exists when the rate at which reactants form products is the same as the rate at which products form reactants.
Explanation:
When the concentration of both the reactants and products do not change with time then it means the chemical reaction has reached to a state of chemical equilibrium.
For example,
Therefore, we can conclude that a chemical equilibrium exists when the rate at which reactants form products is the same as the rate at which products form reactants.
The elements of same group are placed in same group as they have similar properties. So Calcium is the element which resembles Mangesium.
Calcium and Magnesium both are alkaline earth metals.
They have similar properties as they have similar outer or valence shell electronic configuration
The general electronic configuration of alkaline earht metal is ns2
The electronic configuration of Mg [atomic number 12] and Ca [atomic number 20] are
and
respectively.