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NEET UG, JEE Main Chemistry questions: Online Multiple Choice Questions (MCQs) with answers for NEET and JEE Main aspirants, Chemistry Practice questions, MCQs, Past Year Questions (PYQs), NCERT Questions, Question Bank, Class 11 and Class 12 Questions, NCERT Exemplar Questions ...   ऐल्डॉल संघनन- यह अभिक्रिया उन एल्डिहाइड अथवा कीटोन द्वारा दी जाती है जिनमें अल्फा हाइड्रोजन होते हैं । ऐसे एल्डिहाइड अथवा कीटोन के दो अणु तनु क्षार dilute NaOH  की उपस्थिति में संघनित होकर बीटा- हाइड्रोक्सी एल्डिहाइड अथवा कीटोन बनाते हैं जिसे ऐल्डॉल भी कहते हैं ।  Example 1 –  एसीटैल्डिहाइड में ऐल्डॉल संघनन  होने पर 3- हाइड्रोक्सी ब्यूटेनल बनता है । क्रॉस ऐल्डॉल संघनन –  जब दो भिन्न एल्डिहाइड अथवा कीटोन के अणुओं के मध्य ऐल्डॉल संघनन होता है तो उसे क्रॉस ऐल्डॉल संघनन कहते हैं ।  Example-2  एसीटैल्डिहाइड तथा फॉर्मेल्डिहाइड के मध्य ऐल्डॉल संघनन । बेयर विलिजर ऑक्सीकरण अभिक्रिया – जब कीटोन,  परॉक्सी अम्ल जैसे C 6 H 5 COOOH  के साथ अभिक्रिया करते हैं तो एस्टर बना...

NEET UG, JEE Main Chemistry questions: Online Multiple Choice Questions (MCQs) with answers for NEET and JEE Main aspirants, Chemistry Practice questions, MCQs, Past Year Questions (PYQs), NCERT Questions, Question Bank, Class 11 and Class 12 Questions, NCERT Exemplar Questions ... 1. In the ground state of the H-atom, the electron is : a)In the second shell b)In the nucleus c) Nearest to the nucleus d)Farthest from the nucleus 2. Atoms consist of electrons, protons and neutrons. If the mass attributed to neutron was halved and that attributed to the electrons was doubled, the atomic mass of 6C 12 would be approximately: a) Same  b)Doubled  c) Halved  d)Reduced by 25% 3. The number of electrons in a neutral atom of an element is equal to its: a) Atomic weight  b)Atomic number  c) Equivalent weight  d)Electron affinity 4. Which particle contains 2 neutrons and 1 proton? a) 1H2 b) 2He4 c) 1T3 d) 1D2 5. The highest number of unpaired electrons are in a) Fe...

NEET UG, JEE Main Chemistry questions: Online Multiple Choice Questions (MCQs) with answers for NEET and JEE Main aspirants, Chemistry Practice questions, MCQs, Past Year Questions (PYQs), NCERT Questions, Question Bank, Class 11 and Class 12 Questions, NCERT Exemplar Questions ... 1. Mg2+ is isoelectrionic with a) Cu2+  b)Zn2+  c) Na+  d)Ca2+ 2. The first orbital of H is represented by : ψ =1π(1a0)3/2e―r/a0 , where a0 is Bohr′s radius. The probability of finding the electron at a distance r, from the nucleus in the region dV is: a) ψ2dr  b) ψ24πr2dv  c) ψ24πr2dr  d) ψdv 3. The correct statement about proton is a)It is a nucleus of deuterium  b)It is an ionized hydrogen atom c) It is an ionized hydrogen molecules  d)It is an α- particle 4. The energy ∆E corresponding to intense yellow line of sodium of λ, 589 nm is: a) 2.10 eV  b)43.37 eV  c) 47.12 eV  d)2.11 kcal 5. One electron volt is: a) 1.6 × 10―19 erg  b)1.6 × 10―12erg...