Answer:

What is Radical

In chemistry, a radical is an atom, molecule, or ion that has an unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes.

What is valency

In chemistry, the valence or valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules.

How many atoms are there in NH⁴ to form a radical.

Ammonium is an important source of nitrogen for many plant species, especially those growing on hypoxic soils. However, it is also toxic to most crop species and is rarely applied as a sole nitrogen source. The ammonium (more obscurely: aminium) cation is a positively charged polyatomic cation with the chemical FORMULA NH4+. It is formed by the protonation of ammonia (NH3). Ammonium is also a general NAME for positively charged or protonated SUBSTITUTED amines and QUATERNARY ammonium cations (NR4+), where one or more hydrogen atoms are replaced by organic radical groups (indicated by R). Ammonium is found to be associated with N-acetylglutamate synthetase deficiency, which is an inborn error of metabolism.

Thank you .

If it is correct and suitable for you please mark my answer as brilianist.