One of these is unique to proteins*1 pointNitrogenCarbonHydrogenOxygenSulphur

One of these elements is unique to proteins. Let's analyze each option:

1. Nitrogen: Nitrogen is an essential element found in proteins. It is a crucial component of amino acids, which are the building blocks of proteins. Therefore, nitrogen is not unique to proteins.

2. Carbon: Carbon is present in all organic compounds, including proteins. It forms the backbone of amino acids and is necessary for the structure and function of proteins. Therefore, carbon is not unique to proteins.

3. Hydrogen: Hydrogen is also found in all organic compounds, including proteins. It is involved in various chemical reactions and contributes to the stability and folding of proteins. Therefore, hydrogen is not unique to proteins.

4. Oxygen: Oxygen is another element commonly found in proteins. It is involved in the formation of peptide bonds between amino acids and plays a role in protein structure and function. Therefore, oxygen is not unique to proteins.

5. Sulphur: Sulphur is the correct answer. It is the only element listed that is unique to proteins. Sulphur is present in certain amino acids, such as cysteine and methionine, and is crucial for the formation of disulfide bonds, which contribute to the three-dimensional structure of proteins.

In conclusion, out of the given options, sulphur is the element that is unique to proteins.