A nitrogen molecule consists of two nitrogen atoms bonded together by a triple bond. A triple bond is composed of one sigma (\( \sigma \)) bond and two pi (\( \pi \)) bonds. The \( \sigma \) bond is formed by the head-on overlap of atomic orbitals, while the \( \pi \) bonds are formed by the lateral overlap of p-orbitals.
In \( N_2 \), each nitrogen atom contributes three electrons to form the triple bond, satisfying the octet rule for both atoms. This results in one \( \sigma \) bond and two \( \pi \) bonds.
Final Answer: The covalent bonds in a nitrogen molecule consist of \( \mathbf{\text{one } \sigma \text{ bond and two } \pi \text{ bonds}} \), which corresponds to option \( \mathbf{(3)} \).