Find the conjugate acid of NH₂⁻

The correct option/answer is NH₃.

To find the conjugate acid of a chemical species, we follow the Brønsted-Lowry acid-base theory.

According to the Brønsted-Lowry definition:
1. An acid is a proton (H⁺) donor.
2. A base is a proton (H⁺) acceptor.

When a base accepts a proton (H⁺), it forms its conjugate acid. The formula for the conjugate acid is found by adding one hydrogen atom (H) and increasing the overall charge of the species by +1.

Let's apply this step-by-step to the amide ion, NH₂^-:
1. Start with the formula of the base: NH₂^-.
2. Add a proton (H⁺) to the base:
$${\mathrm{NH}}_2{-}^{}+H^{+}\to {\mathrm{NH}}_3$$

3. Determine the chemical formula and net charge:
- The number of nitrogen (N) atoms remains 1.
- The number of hydrogen (H) atoms increases from 2 to 3, giving H₃.
- The initial electrical charge is -1. Adding a charge of +1 from the proton results in a net charge of 0 ($-1+1=0$).

Therefore, the conjugate acid of NH₂^- is ammonia, which is represented by the chemical formula NH₃.