Consider this equilibrium:
n2(g) + 3h2(g) 2nh3(g) + energy.

certain conditions provide less than 10% yield of nh3 at equilibrium. which statement describes this equilibrium?

This is the complete answer, including the set of answer choices:

Certain conditions provide less than 10% yield of NH3 at equilibrium. Which statement describes this equilibrium?

A. The Keq is large and products are favored.
B. The Keq is small and products are favored.
C. The Keq is large and reactants are favored.
D. The Keqis small and reactants are favored.
E. The conditions of the reaction must be known to answer the question

To answer you must know that the equilibrium yield is the quantity of product obtained.

In this case it is 10% of NH3.

That means that the equilibrium is more favorable to the reactants.

Given that Ke relates the concentration of products / concentration of reactants, the answer is the Ke is small and reactants are favored

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom.