Question

____ is a mixture of sand and clay.
A. Clay
B. Humus
C. Silt
D. Loam

Answer 1

Hint: The word mixture refers to a material that is made up of a physical combination of two or more different substances. Sand is a granular substance which is made up of finely divided rock particles and mineral particles. Clay is a type of natural soil which contains hydrous aluminium phyllosilicates. It develops plasticity when it comes in contact with liquid.

Complete answer: Mixtures can be defined as a product of mixing chemical substances such as elements and compounds or mechanical blending of two or more different substances. The physical properties of different materials in a mixture are retained and exhibit their properties even in the mixture. Loam is a type of soil composed of sand, silt and smaller amounts of clay. Loam soil is the ideal plant-growing medium. Different types of loam soil are available with each having slightly different characteristics.
a) Clay is made up of a mineral called hydrous aluminium phyllosilicates. A variable amount of water is trapped in the mineral structure of the clay. The plasticity of the clay is due to its geometry and water content. It becomes hard, non-plastic, and brittle upon firing or drying.
b) Humus refers to the mature or natural compost extracted from the woodland. It is most commonly used as a soil conditioner. Humus is the organic content of the soil that is amorphous in nature and affects the bulk density of soil and contributes to its retention of moisture and nutrients.
c) Silt is a type of soil which contains granular materials whose size ranges between the sand and the clay. Quartz and feldspar are the mineral origin of silt. Silt is typically non-sticky and has a plastic feel.
So, option D is the correct answer.

Note: Bricks made up of mud, sand, loam and water with a binding material such as rice husks or straw, have been used in construction since ancient times. Loam soil can be further classified as silt loam, clay loam, sandy loam, and silty clay loam.