The $pH$ of a fertile soil is usually around

Crop plants need various fertilizers for their growth. Their yield is limited by that fertilizer which is present in relatively minimum. The principle contained in this statement was enunciated by

Which of the following soil types has the least porosity?

Factors which determine to a large extent the vegetation of any area are:
$I.$ $pH$ of soil
$II.$ Mineral composition of the soil
$III.$ Water holding capacity of soil
$IV.$ Weather condition
Choose the correct option.

In vertebrate animals,what fraction of the total phosphorus is incorporated into teeth and bones (in $\%$)?

Minerals are present in our body in: