Soil (NCERT Solutions,Class 7)

Tick the most suitable answer in question 1 and 2.

(1)In addition to the rock particles, the soil contains

(i) air and water

(ii) water and plants

(iii) minerals, organic matter, air and water

(iv) water, air and plants

Ans-

(i) air and water

(ii) water and plants

(iii) minerals, organic matter, air and water   √

(iv) water, air and plants

(2) The water holding capacity is the highest in

(i) sandy soil

(ii) clayey soil   √

(iii) loamy soil

(iv) mixture of sand and loam

Ans-

(i) sandy soil

(ii) clayey soil   √

(iii) loamy soil

(iv) mixture of sand and loam

(3) Match the items in Column I with those in Column II:

       Column I                                                                        Column II

(i) A home for living organisms                                    (a) Large particles

(ii) Upper layer of the soil                                             (b) All kinds of soil

(iii) Sandy soil                                                                  (c) Dark in colour

(iv) Middle layer of the soil                                           (d) (Small particles and packed tight

(v) Clayey soil                                                                   (e) Lesser amount of humus

Ans- The match of the column I with column II are given below:

(i)- (b)

(ii)- (c)

(iii)- (a)

(iv) – (e)

(v)- (d)

(4) Explain how soil is formed.

Ans- Soil is formed by the processes of weathering. The processes in which rocks are break down by the action of wind, water and climate to form soil is called weathering. The nature of soil depends upon the originator rock and the vegetation grows on it.

(5) How is clayey soil useful for crops?

Ans- The pores of clayey soil is small in size and tightly packed. It can retain the water. Hence its percolation rate is low. So, clayey soil is good for the crops like cereals and paddy.

(6) List the differences between clayey soil and sandy soil.

Ans-

Differences between clayey soil and sandy soil

S.N. Clayey soil Sandy soil
1. Colour yellow to red Colour grey to white
2. Pores small in size Pores large in size
3. Particles are tightly packed Particles are loosely packed
4. Water can retain Water can not retain
5. Low percolation rate High percolation rate
6. Low infiltration rate High infiltration rate
7. Rich in humus Not rich in humus

(7) Sketch the cross section of the soil and label the various layers.

Ans- The cross section of the soil and its layer is labeled and shown below:

schoolhelpbygunjan.wordpress.com | Soil | Diagram | Soil profile | Notes | NCERT | Class 7

(8) Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.

Ans-

Percolation rate (mL/min) = amount of water (mL)/percolation time (min)

Percolation time = 40 min (given)

Amount of water = 200mL

Percolation rate (mL/min)= 200/40

= 5 mL/min

(9) Explain how soil pollution and soil erosion could be prevented.

Ans-Prevention of soil pollution-

(i)We should not use polythene bags and plastics. Polythene bags and plastics kill the living organism of soil.

(ii)The waste products should be reduced.

(a) Say no to paper if it is possible. Use e- bill and e- receipts.

(b) Put animal waste in septic tanks.

(iii) Waste products and chemical should be treated before they are released into the soil.

(iv) The use of pesticide should be minimized.

(v)Reuse and recycle the used products.

(a) Reuse bath water in gardens

(b) Reuse other side of paper.

(c) Make dusters from old cloths.

Prevention of soil erosion-

(i) Prevent deforestation.

(ii) Grow grass in gardens.

(iii) Reduce grazing on fertile land.

(iv) Improve drainage in your garden because rain can wash away soil.

(v) Don’t over watering in your garden, farms and fields because over watering can erode soil.

(10) Solve the following crossword puzzle with the clues given:

Soil,Q 10,NCERT,class 7

Across

  1. Plantation prevents it.
  2. Use should be banned to avoid soil pollution.
  3. Type of soil used for making pottery.
  4. Living organism in the soil.

Down

  1. In desert soil erosion occurs through.
  2. Clay and loam are suitable for cereals like.
  3. This type of soil can hold very little water.
  4. Collective name for layers of soil.

Ans- The answer of given puzzle is shown in the grid below:

Soil,A 10,NCERT,class 7

Helping Topics

Soil

Practice sheet

Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.

Differences between clayey soil and sandy soil

Prevention of soil pollution

Prevention of soil erosion

 

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