Last seen: May 1, 2022
Correct answer: (d) nutrient enrichment (eutrophication). Explanation: Addition of phosphate fertilizers to water leads to nutrient enrichment (eu...
Correct answer: (a) The average residence time of NO is one month. Explanation: The average residence time of NO is 4 days.
Correct answer: (b) re-radiation of I.R. rays by CO2 and H2O.
Correct answer: (c) (ii) and (iv) Explanation: CO and oxides of Nitrogen are poisonous gases present in automobile exhaust gases.
Correct answer: (c) SO2 and NO2 Explanation: SO2 and NO2 are responsible for the discoloured and lusterless nature of marble.
Correct answer: (b) I and II Explanation: Pesticides and synthetic fertilizers pollute the soil.
Correct answer: (a) methemoglobinemia Explanation: Excessive concentration of nitrate in drinking water is harmful and can cause methemoglobinemia...
Correct answer: (c) Freons, chlorofluorocarbons, are inert. Chemically, they do not react with ozone in stratosphere. Explanation: Freons and chlo...
Correct answer: (b) methane and CO2 in atmosphere. Explanation: The main gas responsible for the global warming is carbon dioxide. Other contribut...
Correct answer: (c) Microorganisms present in the soil Explanation: CO is converted into CO2 by microorganism present in soil.
Correct answer: (a) London smog is oxidising in nature Explanation: London smog is reducing in nature.
(i) In the 1st, 2nd and 3rd transition series, the 3d, 4d and 5d orbitals are respectively filled. We know that elements in the same vertical column g...
Magnetic moment (μ) is given as μ = For value n = 1, μ = = = 1.732 For value n = 2, μ = = = 2.83 For value n = 3, μ = = = 3.87 For valu...
The properties of the elements of the first transition series differ from those of the heavier transition elements in many ways. (i) The atomic siz...
Atomic number - Electronic configuration 61 → [Xe]544f55d06s2 91 → [Rn]865f26d17s2 101 ...
Electronic configuration The general electronic configuration for lanthanoids is [Xe]544f0-145d0-16s2 and that for actinoids is [Rn]865f1-146d0-17s...
The lanthanides that exhibit +2 and +4 states are shown in the given table. The atomic numbers of the elements are given in the parenthesis. +2 → ...
Ce: 1s22s22p63s23p63d104s24s24p64p64d105s25p64f15d16s2 Magnetic moment can be calculated as: μ = Where, n = number of unpaired electrons Th...
The last element in the actinoid series is lawrencium, Lr. Its atomic number is 103 and its electronic configuration is [Rn]5f146d17s2. The most commo...
Lanthanoids primarily show three oxidation states (+2, +3, +4). Among these oxidation states, +3 state is the most common. Lanthanoids display a limit...