Question

Which one of the following factors does not lead to soil formation in nature?
A) Sunlight
B) Water
C) Wind
D) Polythene bag

Answer 1

Soil is the outermost layer of our Earth (crust), which forms the upper surface of land and supports plant growth. The minerals present in soil can supply a variety of nutrients to life forms. It is an important resource that decides the diversity of life in an area.

Complete answer:
The formation of soil occurs by the process of weathering. It is the breakdown of huge rocks into smaller mineral particles.

Sunlight heats up rocks during the day, so that they expand and at night these rocks cool down and contract. The expansion and contraction of rocks do not occur at same time and this leads to the formation of cracks.

Water helps in the formation of soil in two ways – firstly, it could get into cracks in the rocks formed due to uneven heating by the Sun and when this water freezes it causes cracks to widen. Secondly, fast flowing water often carries big and small particles of rocks downstream and these rocks rub against the other rocks which result in the breakdown of the rocks into smaller particles.

Wind acts similarly as water. Strong winds also erode rocks down and also carry sand from one place to another like water does.

So, the correct answer is option (D) Polythene Bag because these cannot be broken down into smaller particles by the process of weathering.

Note: Living organisms also lead to the formation of soil. The lichens grow on the surface of rocks and while growing, they release certain substances that cause the rock surfaces to powder down and form a thin layer of soil. Other small plants like mosses and roots of big trees also break the rocks.