A(n) is an organic compound in which a carbonyl group is bonded to two different carbon atoms.

Answer : A Ketone is an organic compound in which a carbonyl group is bonded to two different carbon atoms.

Explanation :

A Ketone is an organic compound having a structure where R and R' can be different carbon containing substituents.

Ketone is a compound in which the a carbonyl group is bonded to the two different carbon atoms which are R and R' and there is a double bond present between the carbon and oxygen atom.

Some examples of ketones are, acetone, propanone, butanone, etc.

Hence, a Ketone is an organic compound in which a carbonyl group is bonded to two different carbon atoms.

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.