Reaction of ammonia with excess $$Cl_2$$ gives:

We start with the observation that ammonia, $$\text{NH}_3$$, can behave either as a reducing agent or as a nucleophile, and its products with chlorine depend strongly on the relative amounts of the two reactants present.

First, let us recall the two extreme cases (we shall soon focus on the one that involves excess chlorine):

1. When chlorine is taken in limited quantity, the redox reaction dominates. The textbook equation is

$$8\,\text{NH}_3 + 3\,\text{Cl}_2 \;\longrightarrow\; \text{N}_2 + 6\,\text{NH}_4\text{Cl}.$$

This gives molecular nitrogen and ammonium chloride.

2. When chlorine is taken in excess, the substitution reaction goes all the way; each hydrogen atom on the nitrogen of ammonia can be replaced by a chlorine atom. The product of full substitution is nitrogen trichloride $$\text{NCl}_3$$. The three displaced hydrogens combine with three more chlorine atoms (from the excess chlorine) to give hydrochloric acid $$\text{HCl}$$. The corresponding balanced equation is

$$\text{NH}_3 + 3\,\text{Cl}_2 \;\longrightarrow\; \text{NCl}_3 + 3\,\text{HCl}.$$

Let us verify each stoichiometric step explicitly:

• One molecule of $$\text{NH}_3$$ contains one nitrogen and three hydrogens.

• Replacing one hydrogen by chlorine requires one molecule of $$\text{Cl}_2$$ (because each $$\text{Cl}_2$$ supplies two chlorine atoms; one atom substitutes at nitrogen, the other atom pairs up with the ejected hydrogen to form $$\text{HCl}$$). Since there are three hydrogens on ammonia, full substitution needs three such $$\text{Cl}_2$$ molecules.

• After three substitutions, all three H atoms are displaced, giving $$\text{NCl}_3$$. The three displaced hydrogens each pair with a leftover chlorine atom to furnish three molecules of hydrochloric acid. Symbolically, for each hydrogen removed:

$$\text{H}^{\;(\text{from NH}_3)} + \text{Cl}^{\;(\text{from Cl}_2)} \;\longrightarrow\; \text{HCl}.$$

• Collecting these three identical steps yields the overall reaction already written.

Thus, with excess chlorine we exclusively obtain nitrogen trichloride and hydrochloric acid.

Now we compare with the given options:

A. $$\text{NH}_4\text{Cl}$$ and $$\text{N}_2$$ - those are the products for limited chlorine, not excess.

B. $$\text{NH}_4\text{Cl}$$ and $$\text{HCl}$$ - ammonium chloride is absent when chlorine is in excess.

C. $$\text{NCl}_3$$ and $$\text{NH}_4\text{Cl}$$ - ammonium chloride again appears only in the limited-chlorine route.

D. $$\text{NCl}_3$$ and $$\text{HCl}$$ - exactly matches the products we have just derived for excess chlorine.

Hence, the correct answer is Option D.