Bacillus ramosus is an ammonifying bacterium while Nitrosomonas is a `N_2` fixing bacterium.

Explanation

To determine whether the statement "Bacillus ramosus is an ammonifying bacterium while Nitrosomonas is a nitrogen-fixing bacterium" is true or false, we can analyze the roles of each bacterium in the nitrogen cycle.

### Step-by-Step Solution:

1. **Identify Bacillus ramosus:**
- Bacillus ramosus is known to be an ammonifying bacterium. Ammonifying bacteria are responsible for the process of ammonification, where they decompose organic matter and convert nitrogenous compounds (like proteins and urea) into ammonia (NH3).

2. **Identify Nitrosomonas:**
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