Bacteria and archaea carry out the process of nitrogen fixation, which reduces atmospheric nitrogen, N2, to the biologically useful form NH3, also called ammonia. The nitrogenase complex consists of two proteins, reductase and nitrogenase, which catalyze the reactions of nitrogen fixation. Match each structural feature or function with the corresponding component of the nitrogenase complex. a. also called the molybdenum—iron protein, or the MoFe protein
b. transfers electrons from a donor, such as frrredoxin, to the other component.
c. Homodimer
d. Heterotetramer

1. Reductase
2. Nitrogenase

a. Nitrogenase

b. Reductase

c. Reductase

d. Nitrogenase

Explanation:

Reductase is a enzyme which promotes chemical reduction for a substance. It is also known as iron protein as iron is main component in reductase. Nitrogenase are molybdenum because they sulfur as co factor

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.