When one fission reaction instigates exactly one more fission reaction it is called?

(1) CO

Explanation: A molecule is said to be polar when it has atoms with different electronegativities. The more is the difference in electronegativity, the more polar is the bond.

Electronegativity of carbon and oxygen are 2.5 and 3.5 respectively. Thus difference is (3.5-2.5)=1.0.

Electronegativity of hydrogen and Iodine are 2.1 and 2.7 respectively. Thus difference is (2.7-2.1)=0.6.

Electronegativity of nitrogen and oxygen are 3.0 and 3.5 respectively. Thus difference is (3.5-3.0)=0.5.

Electronegativity of hydrogen and chlorine are 2.1 and 3.0 respectively. Thus difference is (3.0-2.1)=0.9.

Thus as the highest difference of electronegativity is among carbon and oxygen, CO is the most polar.