Answer: Option A. ->
:

Identification: 1 Mark
Justification: 2 Marks
(a) Lichens and (b) Mosses.
Lichens and mosses release substances which break down the rocks resulting in the formation of soil. The mode of action here is chemical. 
Lichens grow on the surface of rocks. While growing, they release certain substances that cause the rocks to break and form a thin layer of soil. Other small plants mosses, are able to grow on this surface now and they cause the rocks to break further. The roots of big trees sometimes go into cracks in the rocks and as the roots grow bigger, the size of the cracks increase.

Answer: Option A. ->
:
Each reason: 1 Mark
(a)  This is so because of excessive use of water which depletes the ground water.
(b)  Towns and cities have asphalted roads and vast areas of soil are concreted. As a result, rain water cannot percolate to recharge ground water and the ground water level decreases further. Villages have larger areas of open soil surface and fewer asphalted roads and concrete surfaces.
 

Answer: Option A. ->
:

Definition: 1 Mark
Causes: 2 Marks
The contamination of soil due to excessive use of chemicals and harmful waste products like fertilizers, insecticides, industrial wastes etc. is called soil pollution.
Following are the causes of soil pollution:

1. Excessive use of chemical fertilizers
2. Waste disposal from industries
3. Mining activities

Answer: Option A. ->
:

Soil type: 1 Mark
Reason: 1 Mark
Idol makers use rich clayey soil mixed with alluvial soil.
Clayey soil retains moisture and becomes very sticky when wet. It becomes easy for the sculptors to carve out idols using this soil. Furthermore when dry, clayey soil becomes so hard that baking becomes redundant.

Answer: Option A. ->
:

Statement: 1 Mark
Explanation: 2 Marks
This statement is absolutely correct.
Clayey soil has an important characteristic that it can retain water and moisture and therefore it is very useful for growing cereals like wheat, gram etc. 
Sandy soils are highly porous and have very little water retention capacity. Plants require water for photosynthesis. In the absence of water in the soil, they will wilt and die.

Answer: Option A. ->
:
Each factor: 1 Mark
Any two:
Soil formation is influenced by the following factors:
1.Organism
2.Topography
3.Time
4.Climate
5.Parent material

Answer: Option A. ->
:

Each difference: 1 Mark
1. Physical weathering does not change the chemical composition of the rock whereas chemical weathering changes the chemical composition.
2. Physical weathering may result due to temperature, pressure, snow, etc. whereas chemical weathering mainly takes place due to the action of some chemicals.

Answer: Option A. ->
:
Statement: 1 Mark
Reasons: 2 Marks
No, it is not a good practice to remove grass and small plants that are growing in an open, unused field.
Plants cover the soil surface and their roots bind the soil particles and hold them in place. During strong winds and rains, they prevent soil erosion and thereby protect the top soil. This stops patches of land turning into deserts after long periods of time. 

Answer: Option A. ->
:
Preventing soil erosion: 1 Mark each
Soil can be conserved by following any of the methods mentioned below:
Any three:
1. Practicing no-till farming. In no-till farming, crops are allowed to remain rather than being ploughed at the end of the season. This keeps the soil tight.
2. Using terrace farming or contour farming. In this method of farming, crops are planted on steps to prevent soil from being run off with rainwater.
3. Planting rain gardens. Rain gardens are planted along slopes of a hill to keep the soil tight. 
4. Using a rain barrel. Rain barrels store water instead of letting it run off, eroding soil along with it.
5. Planting windbreaks. Windbreaks or shelterbelts stop the flow of wind, preventing soil erosion by wind.
6. Restoring wetlands. This gives the water some place to go without eroding the soil in other places

Answer: Option A. ->
:

Each point: 1 Mark
Any 3
(a)  For enabling easy root growth
(b)  For easier percolation of water
(c)  For aerating the soil/enabling air to get into deeper layers of soil
(d)  For removing the weeds​​​​​​​