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JEE-Main, unlike JEE-Advanced, has a fixed exam structure and is not subject to change every year. Up until 2018, the JEE-Main Paper-I was three hours long and consisted of thirty questions in each of the three subjects (physics, chemistry and maths). 4 marks are awarded for correct answers and 1 mark is deducted for incorrect answers.
The JEE-Advanced exam was held on 3 October 2021. JEE-Advanced 2022 was scheduled to be held on 3 July 2022 in the usual two sessions - Morning and Afternoon (both compulsory). However, with 2022 JEE-Main being postponed from April/May to 20–29 June/21–30 July, JEE-Advanced 2022 was also postponed and subsequently held on 28 August 2022.
The number of attempts which a candidate can avail at the examination is limited to three in consecutive years. As of 2018, the top 2,24,000 rankers of JEE-Main will qualify to take the second and final level of examination: JEE-Advanced. this number of 2.24 lakh is not fixed this may vary as per difficulty level of paper of JEE-Main. [7]
Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23 Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl).
There are 20 isotopes of sodium (11 Na), ranging from 17 Na to 39 Na (except for the still-unknown 36 Na and 38 Na), [4] and five isomers (two for 22 Na, and one each for 24 Na, 26 Na, and 32 Na). 23 Na is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weight of 22.989 769 ...
Sodium hydride is the chemical compound with the empirical formula Na H.This alkali metal hydride is primarily used as a strong yet combustible base in organic synthesis.NaH is a saline (salt-like) hydride, composed of Na + and H − ions, in contrast to molecular hydrides such as borane, silane, germane, ammonia, and methane.
Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. As a result, sodium usually forms ionic compounds involving the Na + cation. [1] Sodium is a reactive alkali metal and is much more stable in ionic compounds. It can also form intermetallic compounds and organosodium compounds.
The formula Na 2 SO 3 denotes that the cation is sodium, or Na +, and that the anion is the sulfite ion (SO 2− 3). Therefore, this compound is named sodium sulfite. If the given formula is Ca(OH) 2, it can be seen that OH − is the hydroxide ion.