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

Which of the following statements are true? If false,correct them:
$(a)$ Boron deficiency leads to stout axis.
$(b)$ Every mineral element that is present in a cell is needed by the cell.
$(c)$ Nitrogen as a nutrient element,is highly immobile in the plants.
$(d)$ It is very easy to establish the essentiality of micronutrients because they are required only in trace quantities.

Select the correct match for $X$ and $Y$:

Column $X$	Column $Y$
$(1)$ Mycorrhiza	$(P)$ Free-living $N_2$-fixer
$(2)$ Nostoc	$(Q)$ Phosphorus absorption
$(3)$ Azospirillum	$(R)$ Leguminous plants
$(4)$ Rhizobium	$(S)$ Autotrophic $N_2$-fixer

Which of the following statements is incorrect?

Assertion : Plants absorb sulphur in the form of sulphate ions.
Reason : Sulphur bacteria are required for the formation of sulphate.

Identify the $INCORRECT$ statement regarding the role of minerals in plants.