We have Kc = 4.2 x 10^-2 (given but missing in the question)
and When the balanced equation for this reaction is:
PCl5(g) ↔ PCl3(g) + Cl2(g)
so, according to the Kc formula:
Kc = the concentration of products / the concentration of the reactants
so, to get the concentration of the reactants in equilibrium, the concentration of the products / the concentration of the reactants should equal the Kc value which is given in the question (missing in your question).
So by substitution in Kc formula:
Kc = [PCl3]*[Cl2] / [PCl5]
4.2 x 10^-2 = 0.18 * 0.25 /[PCl5]
∴[PCl5] = 0.18*0.25 / 4.2x10^-2 = 1.07
So the concentration of the reactants in equilibrim = 1.07
Answer : The balanced equation is,

Explanation :
According to the Bronsted Lowry concept, Bronsted Lowry-acid is a substance that donates one or more hydrogen ion in a reaction and Bronsted Lowry-base is a substance that accepts one or more hydrogen ion in a reaction.
The balanced chemical reaction will be,

In this reaction, hydrofluoric acid is act as a Bronsted Lowry-acid because it donate one hydrogen ion to
and
is act as a Bronsted Lowry-base because it accept one hydrogen ion from
.
Answer:
Throughout the explanation section, the reason behind the given statement is described.
Explanation:
- The chemicals thus produced were indeed opposite or separate from the reaction mixture, this same reaction wouldn’t change when it's more balanced than some of the reactants.
- Another reason is that the development of advanced organisms, as well as chemical alterations, is irreversible throughout nature cant undo the chemical modifications.
Answer:
The answer to your question is: C. The specific latent heat of fusion
Explanation:
A. The specific latent heat of vaporization Specific latent heat of vaporization indicates the transition from liquid to vapor, but we are not looking for this definition. This answer is wrong.
B. The specific heat
indicates the amount of heat needed to increase the temperature of water 1°C, so this answer is wrong.
C. The specific latent heat of fusion
. This heat indicate the transition from solid ie to liquid, so this is the right answer.
D. The internal energy measures the energy of the molecules of a substance, so this answer is wrong.
Answer:
magnesium + oxygen ----> magnesium oxide