What functional groups are in Caffeine ?

Hint :We know that to solve the given problem, we should have the basic knowledge of Caffeine and functional groups. Organic Chemistry plays an important role in the manufacturing of many daily use products, Caffeine is one of them. It belongs to the methylxanthine class.

Complete Step By Step Answer:
Functional groups are specific groups of atoms or bonds in a compound which is responsible for the characteristic chemical reaction of that compound. Same functional group will behave in similar fashion, regardless of the compound of which it is part of. It is a common psychoactive drug which increases and alters the psychological changes in our body. It is made up of organic compounds. So, it definitely contains some functional groups.
Step-1: We should know that functional groups are always specific containing the precise atoms in the similar molecular formula always. They have some specific chemical and physical properties that do not change.
     
Step-2: There are many functional groups which should be remembered correctly with their formulas. Some of them are Carboxylic acid ( $ -COOH $ ), Amide ( $ -CON{{H}_{2}} $ ), Ketone ( $ -CO $ ), Aldehyde ( $ -CHO $ ), Alcohol ( $ -OH $ ), Amine ( $ -N{{H}_{2}} $ ) and many more.
Step-3: On studying the structure of Caffeine properly, we can say that they have amide and amine as functional groups. The structure contains $ 1 $ amine and $ 2 $ amide groups. It looked carefully and precisely, an imine group ( $ -C=N $ ) is also present. The general groups like methyl ( $ -C{{H}_{3}} $ ) and alkene ( $ -C=C $ ) groups are also found in the compound.

Note :
Remember that the chemical formula for a functional group or any group changes while in a straight line and in a cyclic structure. So, it should be reminded carefully. An organic compound can contain more than one functional group. To identify the functional group, you must know their formula. For example, if a hydroxyl group is present then its formula is $ -OH. $ For the acidic group, the formula is $ -COOH.~ $