1. Coal and petroleum are the fossil fuels. They are burnt to get energy. Combustion of fossil fuels produces (i) suspended particles, (ii) sulphur oxides; (iii) nitrogen oxides; (iv) carbon dioxide; (v) carbon monoxide; (vi) vapours of hydrocarbons' All these are air pollutants. Hydrocarbons act as aRead more

    Coal and petroleum are the fossil fuels. They are burnt to get energy. Combustion of fossil fuels produces (i) suspended particles,
    (ii) sulphur oxides;
    (iii) nitrogen oxides;
    (iv) carbon dioxide;
    (v) carbon monoxide;
    (vi) vapours of hydrocarbons’ All these are air pollutants. Hydrocarbons act as a source of nitrogen cancer. Along with oxides, they produce ozone and smong. Sulphur and nitrogen oxides give rise to acid rain They are also irritatants and damage eyes and nasal tract.

    See less
    • 4
  2. Root nodules mostly occur in the legume plants. These nodules contain nitrogen fixing bacteria named Rhizobium' The bacteria picks up nitrogen from soil atmosphere and convert it into organic compounds. The same pass into the plant so that legumes (e.g., pea, gram) become rich in proteins and otherRead more

    Root nodules mostly occur in the legume plants. These nodules contain nitrogen fixing bacteria named Rhizobium’ The bacteria picks up nitrogen from soil atmosphere and convert it into organic compounds. The same pass into the plant so that legumes (e.g., pea, gram) become rich in proteins and other nitrogen compounds.

    See less
    • 3
  3. Step farming is also called terracing. It is carried out in the hills because terracing slows down the speed of rain water currents, checks soil erosion and increase water absorption by the soil.

    Step farming is also called terracing. It is carried out in the hills because terracing slows down the speed of rain water currents, checks soil erosion and increase water absorption by the soil.

    See less
    • 3
  4. Fertile soil contains sufficient amount of humus because (i) Humus is required for binding soil particles into crumbs. Crumb formation helps in both hydration and aeration of soil. (ii) Humus makes the soil porous for easy passage of plant roots. (iii) Humus is a source of mineral. (iv) Humus contaiRead more

    Fertile soil contains sufficient amount of humus because (i) Humus is required for binding soil particles into crumbs. Crumb formation helps in both hydration and aeration of soil. (ii) Humus makes the soil porous for easy passage of plant roots. (iii) Humus is a source of mineral. (iv) Humus contains chemicals that promote growth of plants.

    See less
    • 3
  5. Yes, water causes weathering of rocks by following three methods. 1. Wetting and drying. Certain constituents of rocks can pick up moisture and swell up. They contract on drying. Such components (1.e., chemicals) help in breaking of rocks. 2. Frost action. Water seeps into rock crevices and cracks aRead more

    Yes, water causes weathering of rocks by following three methods.
    1. Wetting and drying. Certain constituents of rocks can pick up moisture and swell up. They contract on drying. Such components (1.e., chemicals) help in breaking of rocks.
    2. Frost action. Water seeps into rock crevices and cracks and may freeze if the temperature goes below O°C. Frozen water expands and exerts a huge pressure sufficient to break all rocks.
    3. Abrasion. Beating of rocks by rain and hail, wave action on shores and abrasion caused by trumbling rock fragments in running water batter and grind the rocks into smaller and smaller particles. Water carries these particles depositing them downstream. This produces soil (e.g., sand particles) at a far away place from the parent rock.

    See less
    • 3