Which element is required in comparatively least quantity for the growth of plant?

Which of the following essential element is not properly placed in the given category?

Which mineral nutrients are called critical element for crops?

The mineral nutrient mainly concerning with apical meristematic activity is –

Conversion of ammonia into nitrates through Nitrosomonas is called

Which is free ion present in a cell ?

Which element is not considered as macro nutrient?

Which element can not be placed along with micro nutrients?

Cobalt present in :

Plants obtain Fe in the form of-