Chemistry
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New answer posted
a year agoContributor-Level 10
Pesticides are the chemical compounds used to control the damage caused by pests (insects, rodents etc.)
Example: Aldrin, Dieldrin, B.H.C etc.
Herbicides are the chemicals used to control weeds.
Example: Triazines, Sodium chlorate (NaClO3), sodium arsenite (Na3AsO3).
New answer posted
a year agoContributor-Level 10
1.28 Coordination number is the number of the nearest neighbors with which a given atom is in contact. In an
ionic crystal, the coordination number of an ion refers to the number of oppositely charged ions that
surround that ion.
The coordination number of atoms in a
(a) Cubic close-packed structure is 12.
(b) Body-centred cubic structure is 8
New answer posted
a year agoContributor-Level 10
The major sources of soil pollution are industrial wastes and agricultural pollutants like fertilizers and pesticides. Insecticides like DDT are insoluble in water and are absorbed by plant roots. Many pesticides like Aldrin and Dieldrin are toxic and non-biodegradable, which can enter the higher trophic levels through food chains, causing metabolic and physiological disorders. Industrial wastes comprise of several toxic metals such as Pb, As, Hg, Cd etc.
To control soil pollution, the addition of pollutants to the soil should be avoided. Waste materials should undergo proper treatment and recycling before dumping.
New answer posted
a year agoContributor-Level 10
The amount of oxygen required by bacteria to breakdown the organic matter present in a certain volume of a sample of water is called Biochemical Oxygen Demand (BOD).
New answer posted
a year agoContributor-Level 10
Yes, we observed water pollution near our area due to various human activities like toxic discharges from factories and industrial plants, runoff from agricultural fields, domestic wastes etc.
It can be controlled by preventing the toxic chemicals from entering the water bodies. Regular checks on contamination or rivers, lakes or ponds of toxic compounds need to be done. Use of chemical fertilizers should be avoided to prevent the harmful chemicals from entering the ground water.
New answer posted
a year agoContributor-Level 10
Major Causes of water pollution are:
Pathogens: Pathogens include bacteria and other microorganisms that enter water from domestic sewage and animal excreta.
Human excreta contain bacteria such as Escherichia coli and Streptococcus faecalis, which cause gastrointestinal diseases.
Organic wastes: Organic wastes, when added to water, are decomposed by bacteria, which consume dissolved oxygen in water. When the concentration of dissolved oxygen in water decreases below 6 ppm, the growth of fish is inhibited. The breakdown of organic wastes by anaerobic bacteria produces chemicals that have a foul smell and are harmful to human health.
Ch
New answer posted
a year agoContributor-Level 10
1.27 The different solids are classified below:
a) Ionic solids: Ammonium phosphate (NH4)3PO4), LiBr
b) Metallic solid: Brass, Rb
c) Molecular solids: Tetraphosphorous decaoxide (P4O10), Iodine (I2), P4
d) Network (covalent) solids: Graphite, SiC, Si
e) Amorphous solid: Plastics
New answer posted
a year agoContributor-Level 10
Depletion of ozone layer creates some sort of holes in the blanket of ozone which surrounds us, this is known as ozone hole.
The consequences are:
- With the depletion of ozone layer, more UV radiation filters into troposphere. UV radiations lead to ageing of skin, cataract, sunburn, skin cancer, killing of many phytoplanktons, damage to fish productivity etc.
- It has also been reported that plant proteins get easily affected by UV radiations which leads to the harmful mutation of cells.
- It also increases evaporation of surface water through the stomata of the leaves and decreases the moisture content of the soil.
4. Increa
New answer posted
a year agoContributor-Level 10
3.30. (i) For n = 3, the element belong to 3rd period, p-block element.
The electronic configuration is =1s2 2s2 2p6 3s2 3p4. The element name is sulphur.
(ii) For n = 4, the element belongs to 4th period and since the valence shell has 4 electrons it belongs to group 4.
Electronic configuration= 1s2 2s2 2p6 3s2 3p6 3d2 4s2, and the element name is Titanium (Ti).
(iii) For n = 6, the element belongs to 6th period. Last electron goes to the f-orbital, element is from f-block. It belongs to group = 3
The element is gadolinium (z = 64)
Complete electronic configuration = [Xe] 4 f7 5
New answer posted
a year agoContributor-Level 10
3.29. (i) s-Block elements: ns1-2 where n = 2-7.
(ii) p-Block elements: ns2 np1-6 where n = 2-6.
(iii) d-Block elements: (n-1)d1-10 ns 0-2 where n = 4-7.
(iv) f-Block elements: (n-2)f0-14 (n-1)d0-1 ns2where n = 6-7.
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