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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.
Q. Determine the taste threshold for different sensations? • perceive the individual differences existing for taste stimulation, and • identify your own threshold and iden
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What metals combine with non-metals, the metal atom tends to: (1) Lose electrons (2) Gain electrons (3) Remain electrically neutral (4)
does nitro compounds cause any harmful effect on living things?
The quantum numbers for the outermost electron of an element are given below as n= 1, l=0, m=0, s = 1/2 . The atoms is: (1) Lithium (2) Beryllium (3) Hydrogen (4)
What are the general methods for preparation of cycloalkane
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Q. How to produce Nitrogen on Industrial Level? Ans. Nitrogen is produced by the fractional distillation of liquid air. Air is cooled to liquefy it. The liquid is then all
It is a phenomenon in which compounds have same moleculer formula but different structural formula due to which they posses different physical and chemical properties.
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