Biomechanics and Sports Case Study Based Questions Chapter 8 Class 12 Physical education

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Diagonal Relationship between Beryllium and Aluminium || Relation between Beryllium and Aluminium

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  Diagonal Relationship between Beryllium and Aluminium The ionic radius of Beryllium (Be 2+) is estimated to be nearly 31 pm; the charge/radius ratio Or e/m ratio is nearly the same as that of the Al 3+ ion. Hence beryllium resembles aluminium in these ways. Some of the similarities are given below: » Like Aluminium, Beryllium(be) is not readily attacked by acids H+ donor because of the formation of an oxide film on the surface of the metal by reacting with oxygen, i.e. they are rendered passive by nitric acid. » Beryllium hydroxide[[Be(OH)4]2] dissolves in excess of alkali to give a beryllate ion, [ Be(OH)4]2– just as aluminium hydroxide[Al(OH)3] gives aluminate ion, [Al(OH)4] » The chlorides of metals beryllium and aluminium have Cl– bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong as Lewis acids They are used as Friedel Craft catalysts. » Beryllium(Be) and aluminium(Al) ions have strong tendency to form complexes, (Be...
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                      1. Introduction In this we will learn the full topic about physical world. To know about " What is physics " And about " Scopes of physics " Click on the above link. The word Science originates from the Latin word S c i e n t i a meaning ‘to know’ , ‘knowledge’. Science, in a broad sense, is as old as human species. The early civilisations of Egypt, India, China, Greece, Mesopotamia and many others made vital contributions to its progress. From the sixteenth century onwards, great strides were made in science in Europe. The interplay of theory and observation (or experiment) is basic to the progress of science. Science is ever dynamic. There is no ‘final’ theory in science and no unquestioned authority among scientists. As observations improve in detail and precision or experiments yield new results, theories must account for them, by introducing modifications.  The modifications may not be drastic and...
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Chemical Bonding and molecular structure Multiple choice questions (MCQs) || Chemical bonding MCQs || Chapter 4 class 11 Chemistry MCQs ||

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1. In which of the following, the bond angle between two covalent bonds is the maximum ? (a) H 2 O (b) NH 3 (c)  CO 2 (d) CH 4 Ans : (c) CO 2 2. The hybridisation of C involved in acetylene is  (a) s p² (b) s p³ (c) s p (d) d s p² Ans: (c) s p 3. Which of the following is not correct resonating structure for carbon dioxide ? (a) O=C=0  (b) O - C=0  (c) 0 - C =0  (d) O= C - O Ans: (c) 0 - C =0 4. Which of the following has maximum covalent character? (a) Li I (b) Li F (c)  Li Cl (d) Li Br. Ans: (a) Li I 5. Which of the following exception to octet rule? (a) BF 3 (b)  PF 5 (c)  CO 2 (d) I F 7 Ans: (c)  CO 2 6. For which of the following hybridisation the bond angle is maximum ? (a) s p² (b) s p³ (c) s p (d) d s p² Ans: (c) s p 7. Which one has minimum dipole moment ? (a) Butene-1 (b) cis-Butene-2 (c) trans-Butene-2 (d) 2-Methyl propene. Ans: (c) trans-Butene-2 8. Which of the following has highest lattice energy?  (a) L...
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