Group the following as nitrogenous bases and nucleosides:
Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine.

Explanation

To group the given substances as nitrogenous bases and nucleosides, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Nitrogenous Bases**: These are organic molecules that contain nitrogen and are fundamental components of nucleic acids (DNA and RNA). The common nitrogenous bases include adenine, guanine, cytosine, thymine, and uracil.
- **Nucleosides**: These are formed when a nitrogenous base is attached to a sugar molecule (ribose in RNA or deoxyribose in DNA). Nucleosides do not contain a phosphate group.

...