Question

Assertion: The reaction \[Li + KF \to {{ }}LiF + {{ }}KI\] proceed in the forward direction.
Reason: Fluorine, being more reactive can easily replace iodine.
A. Both Assert and Reason are true and Reason is the correct explanation of Assertion.
B. Both Assertion and Reason are true but Reason is not a correct explanation of Assertion.
C. Assertion is true but Reason is false.
D. Both Assertion and Reason are false.

Answer 1

Hint: When a reaction moves in a forward direction it usually means that the original reactants which were present are being converted to the products.
Whereas in case of backward reactions, the product which was formed, gets converted to the reactant again, and it can only happen in case of reversible reactions.

Complete step by step answer:
Chatelier's principle: When a chemical system that’s at equilibrium is disturbed by a stress, the system will respond in order to relieve the stress. Stresses to a chemical system involve changes within the concentrations of reactants or products, changes within the temperature of the system, or changes within the pressure of the system. The change to the equilibrium position in every case is either toward the forward reaction or a favoring of the reverse reaction. When the forward reaction is favored, the concentrations of products increase, while the concentrations of reactants decrease. When the reverse reaction is favored, the concentrations of the products decrease, while the concentrations of reactants increase.
Now if we consider the assertion part as we remove one of the compound, say potassium iodide from the product side, then the concentration of reactant will increase so reaction would move in the forward direction Or if we add extra compounds, say lithium on the reactant side, the concentration of the reactant will be more than the concentration of the product side, in this case also reaction moves forward reaction.
So, this justifies that the assertion given in the question is correct.
Now if we consider the reason part yes, Fluorine is more reactive than iodine and it can easily replace iodine.Iodine is also a halogen, so both of them have \[7\] electrons in their outermost shell. The difference is that iodine is a larger atom, so the extra electron would go into a shell which is further removed from the positively charged nucleus. As we know that larger the cation stabilizes larger the anion

So the assertion and reason part are correct but Reason is not a correct explanation of Assertion.

So, the correct answer is Option B.

Note: Increasing or decreasing the temperature of a system at equilibrium is also a stress to the system and Fluorine is more reactive than iodine. This is because the valence electrons are much closer to the nucleus in Fluorine than they are to $Cl$ and other halogens, thus more strongly attracted. $F$ is most electronegative, thus it is most reactive