Answer
Oxygen and nitrogen are found in organic compounds. E.g O is found in alcohols, ethers, carboxylic acids compounds etc. N is found in amines and amides compounds.
Calcium is found in inorganic compounds
Step-by-step explanation
All organic compounds have in common the presence of carbon atoms and hydrogen atoms. In addition, different organic compounds may contain oxygen, nitrogen, phosphorous, and other elements like sulfur.
Calcium is found in inorganic compounds.