Which of the following statements is incorrect?

The agent/s which make/s free atmospheric nitrogen available to plants is/are:

Match the following and choose the correct combination from the options given.

Column $I$	Column $II$
$a.$ Potassium	$(i)$ Germination of pollen grains
$b.$ Molybdenum	$(ii)$ Involved in synthesis of auxin
$c.$ Boron	$(iii)$ Involved in stomatal movement
$d.$ Zinc	$(iv)$ Constituent of ferredoxin
$e.$ Sulphur	$(v)$ Component of nitrate reductase

Which of the following statements are incorrect?
$I.$ Hemoglobin,myoglobin,and cytochromes are iron-containing compounds.
$II.$ Copper is important for cell division in plants.
$III.$ Biotin and riboflavin are sulfur-containing vitamins.
$IV.$ Calcium is necessary for the structure of teeth and bones.
$V.$ Manganese is required in the structure of the phosphatase enzyme.

Which of the following plants is used as green manure in crop fields and in sandy soils?

Select the mismatch.