Which are the criteria for essential minerals?

$A$ : All the diverse mineral elements found in plants are not essential for them.
$R$ : Some plants accumulate heavy and toxic minerals such as gold and selenium from the soil.

Which of the following is considered to be the element between macro-nutrients and micro-nutrients?

Which of the following is a non-mineral element?

An element must be considered essential,when
$I.$ the element is necessary for supporting normal growth and reproduction of the plants
$II.$ the deficiency of that particular element can not be met by supplying some other element
$III.$ the element is directly involved in the metabolism of the plants. Choose the correct pair

$A$ : $N, P, K$ are called critical elements.
$R$ : They become deficient easily in soil due to leaching and higher requirement.