Question

15. Swati dissolved some
garden soil in the beaker with
water. After 30 minutes, she
noticed four layers. The layers
in sequence from top to
bottom are​

Answer 1

Soil is comprised of air spaces and organic matter, but mostly mineral particles. There are three kinds of soil minerals, sand, silt and clay. The relative percentage of each of these particles in the soil determines its texture. Sand has the largest soil particles (0.4- to 0.01-inch diameter) and the largest pores between particles. Silt soil particle size is between clay and sand (0.01- to 0.0001-inch diameter). The characteristics of silty soil are similar to those of clay, but are moderated by its larger particle size. Clay soil has the smallest soil particles (less than 0.0001-inch diameter) and the least amount of water and air spaces between particles. Humus is dark, organic material that forms in soil when plant and animal matter decays. The thick brown or black substance that remains after most of the organic litter has decomposed is called as humus. Hence, humus settles at the topmost and sand the lowermost since, its size is maximum.