49.which of the following statements regarding chemical equilibrium is true?
a. equilibrium is shown with a single arrow and/or an equal sign.

b. a system at equilibrium maintains the concentrations of all reactants/products
over time.

c. a system at equilibrium stops.

d. equilibrium is signified only with an equals sign.

Answer : The correct statement is, (b) A system at equilibrium maintains the concentrations of all reactants/products  over time.

Explanation :

Equilibrium reaction : It is a reaction which do not go on completion that means the reactant forms product and the products goes back to the reactants simultaneously.

In a chemical equilibrium reaction, the equilibrium state is achieved when the rate of forward reaction becomes equals to the rate of the backward reaction.

Equilibrium state is the state when the reactants and products are present but the concentrations does not change with time that means there is no changes in the concentration the products and reactants.

Equilibrium is shown with a way arrow like,

A system does not stop at equilibrium.

Hence, the correct statement is, (b)