741. What do you call the rain that contains chemical waste and cause damage to plants and animals?

A. Smog
B. Acid rain
C. Monsoon rain
D. Seasonal rain
✅ The correct answer is option B.
The sulphur oxides (combination of sulphur and oxygen) react with the water vapour in the air to form very strong acids like sulphuric acid (h2so4). these acids fall along with the rain and hence the name acid rain. this rain is very harmful for plant and animal life.

742. During the afternoon the greatest temperature difference between the surface air and the air several meters above occurs on a:

A. Clear, calm afternoon
B. Clear, windy afternoon
C. Cloudy, calm afternoon
D. Cloudy, windy afternoon
✅ The correct answer is option A.
During the afternoon, the greatest temperature difference between the surface air and the air several meters above the ground occurs on a:clear, calm day.

743. The occurrence of pesticides like DDT in higher trophic levels is termed as

A. bioremediation
B. biomagnification
C. biological enhancement
D. biopollution
✅ The correct answer is option B.
Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain.

747. Boron, Zinc and Manganese are usually referred to as

A. Micronutrients
B. Macronutrients
C. Soil Vitamins
D. MBZ nutrients
✅ The correct answer is option A.
Zinc, Chlorine, Boron, Molybdenum, Copper, Iron, Manganese, Cobalt and Nickel are called micro-nutrients. They are called so because they are found and needed by plants in very small amount relative to other nutrients and are least likely to be limiting plant growth and healthy development.

749. A biomass pyramid is important because it illustrates

A. How energy flows through a food web
B. The number of species in each tropic level
C. The biomass of all organisms at each tropic level in a system
D. The number of tropic levels in a system
✅ The correct answer is option D.
Biomass pyramids show how much biomass (the amount of living or organic matter present in an organism) is present in the organisms at each trophic level, while productivity pyramids show the procreation or turnover in biomass.

750. Utilisation of natural resources in moderate manner to remaining something for the next generation is termed as

A. Resettlement
B. Sustainable development
C. Rehabilitation
D. Mutual development
✅ The correct answer is option B.
Sustainable development is the organizing principle for meeting human development goals while simultaneously sustaining the ability of natural systems to provide the natural resources and ecosystem services based upon which the economy and society depend.