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ORIGIN AND ABUNDANCE OF THE ELEMENTS
The synthesis of elements needs nuclear reactions, of which the most important type is the fusion of two light nuclei to prepare one of higher mass and charge. The attractive strong interaction, which holds neutrons and protons together, operates only over very short distances (around 10-15 m) and is opposed at longer size by the electrostatic repulsion between positively charged protons. To get two nuclei close enough together for fusion needs enormously high energies, which are usually found only at high temperatures (above 107 K) in the interior of stars. Under such conditions the chemical properties of components are irrelevant, as no compounds may exist, atoms being in highly ionized states stripped of their electrons.
Gases thrown out by a supernova cool, and can subsequently be incorporated into new stars. The formation of planetary systems can be common in the Universe. Studies suggest that other planets and the Earth formed about the same time as the Sun. While the Sun formed at the center, chemical reactions in the cooler outer parts of the gas concentration produced solid particles, which collected under gravitational forces, first into small bodies known as planetesimals, and subsequently into the planets. In the outer parts of the Solar System temperatures were low enough to form 'ices' of water, carbon dioxide, solid methane and ammonia, which are constituents of the giant planets Saturn and Jupiter.
Isomerism - Organic Chemistry Organic substance comprising the same molecular reaction but differing from each other at least in some physical or chemical properties or both ar
Uses of Polyglycolic acid,Polylactic acid and Polyhydroxybutyrate PGA and PLA (90 : 10) is utilized to form absorbable structure to close an internal of external wound and has
Physical properties of Tri-halides (i) Tri-halides is a sweet smelling colourless liquid. (ii) Tri-halides is heavy liquid. The density of it is 1.485. It boils at 61°C.
(i) Assign appropriate reason for each of observations: (a) Anhydrous ALCI is used as a catalyst. (b) Phosphinic acid behaves as a monoprotic acid. (c) SF6 is not easily h
Tests of chloroform (a) It gives isocyanide test (Carbylamine test). (b) It makes silver mirror with Tollen's reagent. (c) Pure Chloroform does not give white precipitate
what are the value of standard oxidation and standaed reduction potential of water
The energy of an electron in orbit of hydrogen atom is : (1) 13.6/n 4 x eV (2) 13.6/n 3 xeV (3) 13.6/n 2 xeV (4)13.6/nx eV Ans:
What is the diagonal relationship between Beryllium and Aluminium
Q. Show the Liquation in purification of metals? Crude tin, bismuth and lead are purified by liquation. In this process, the impure metal is placed at the top of a sloping hear
What is use of acetonitrile compare to methanol in RP-HPLC Method development? ACN is highly polar as compare to Methanol So give Better resolution for more compound and it has p
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