Which one of the following crops is not a Kharif crop?
[amp_mcq option1=”Rice” option2=”Maize” option3=”Wheat” option4=”Soya bean” correct=”option3″]
Which one of the following crops is not a Kharif crop?
[amp_mcq option1=”Rice” option2=”Maize” option3=”Wheat” option4=”Soya bean” correct=”option3″]
The Silent Valley is located in which one of the following States?
[amp_mcq option1=”Himachal Pradesh” option2=”Jammu and Kashmir” option3=”Jharkhand” option4=”Kerala” correct=”option4″]
Which one of the following is not a female reproductive organ of flower?
[amp_mcq option1=”Style” option2=”Ovary” option3=”Pollen” option4=”Stigma” correct=”option3″]
Which one of the following cell organelles synthesizes its own proteins involving genes present in its DNA?
[amp_mcq option1=”Endoplasmic reticulum” option2=”Plasma membrane” option3=”Plastid” option4=”Lysosome” correct=”option3″]
Which one of the following is a disease for which India has not faced epidemic at any point of time in the past?
[amp_mcq option1=”Cholera” option2=”Plague” option3=”Leukaemia” option4=”Swine flu” correct=”option3″]
In which part of the heart and circulatory system of human body does deoxygenated blood flow?
[amp_mcq option1=”Aorta” option2=”Pulmonary vein” option3=”Left atrium” option4=”Vena cava” correct=”option4″]
Which one of the following statements is correct?
[amp_mcq option1=”Euplectella and Spongilla belong to different phyla of Animalia.” option2=”Sea anemone belongs to phylum Echinodermata.” option3=”Holothuria is a member of phylum Mollusca.” option4=”Scolopendra (Centipede) is a member of phylum Arthropoda.” correct=”option4″]
Catalytic converter transforms waste gases from the engines of many cars into carbon dioxide, nitrogen and water. The catalyst is made of
[amp_mcq option1=”platinum and copper” option2=”molybdenum and copper” option3=”platinum and rhodium” option4=”rhodium and molybdenum” correct=”option3″]
The number of elements in the lanthanoids of the periodic table is
[amp_mcq option1=”8″ option2=”18″ option3=”14″ option4=”32″ correct=”option3″]
In the context of the f-block of the periodic table, which is typically displayed as two rows below the main body, the lanthanoids constitute the upper row. This row consists of 14 elements, starting after Barium (Z=56) and before Hafnium (Z=72) in the main table. These 14 elements are Cerium (58), Praseodymium (59), Neodymium (60), Promethium (61), Samarium (62), Europium (63), Gadolinium (64), Terbium (65), Dysprosium (66), Holmium (67), Erbium (68), Thulium (69), Ytterbium (70), and Lutetium (71).
Given the options, 14 is present and is the standard number of elements represented in the f-block lanthanoid series, corresponding to the filling of the 4f orbitals. While the definition can sometimes include Lanthanum (making it 15), 14 is the number that fits the typical arrangement and f-orbital filling.
Out of the elements phosphorus (P), sulphur (S), chlorine (Cl) and fluorine (F), the elements having the most negative and least negative electron gain enthalpy, respectively are
[amp_mcq option1=”Cl and P” option2=”F and S” option3=”F and Cl” option4=”P and S” correct=”option1″]
Let’s consider the given elements:
– F (Period 2, Group 17)
– Cl (Period 3, Group 17)
– S (Period 3, Group 16)
– P (Period 3, Group 15)
Comparing F and Cl (Group 17): Although the general trend is less negative down a group, Cl has a more negative electron gain enthalpy (-349 kJ/mol) than F (-328 kJ/mol). This is an anomaly due to the very small size of F, where the added electron experiences significant repulsion from existing electrons in the compact 2p subshell.
Comparing Cl and S (same period, different groups): Electron gain enthalpy becomes more negative across the period. Cl is in Group 17, S is in Group 16. So, Cl should have a more negative value than S. (Cl: -349 kJ/mol, S: -200 kJ/mol). This is consistent.
Comparing S and P (same period, different groups): S is in Group 16, P is in Group 15. Group 15 elements have unusually low (less negative) electron gain enthalpies due to the stable half-filled configuration. So, P should have a less negative value than S. (S: -200 kJ/mol, P: -74 kJ/mol). This is consistent.
Ranking the elements by electron gain enthalpy from most negative to least negative:
Cl (-349) > F (-328) > S (-200) > P (-74)
The element with the most negative electron gain enthalpy is Cl.
The element with the least negative electron gain enthalpy is P.
The pair is (Cl, P).