Doubtly
@Doubtly · Joined Feb 2021
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- मैं हैंडसम नहीं हूं लेकिन मैं अपना हाथ किसी ऐसे व्यक्ति को दे सकता हूं, जिसे मदद की जरूरत हो . मैं हैंडसम नहीं हूं लेकिन मैं अपना हाथ किसी ऐसे व्यक्ति को दे सकता हूं, जिसे मदद की जरूरत हो … क्योंकि खूबसूरती की जरूरत दिल में होती है, चे... 1
- What are emulsions? What are their different types? Give example of each type. Emulsions: It is a colloidal system in which both the dispersed phase and the dispersion medium are liquids, e.g., milk consists of small dr... 1
- What are lyophilic and lyophobic sols ? Give one example in each case. Lyophilic colloids: The colloidal solution in which the particles of the dispersed phase have a great affinity (or love) for the dispersion... 1
- Discuss the effect of pressure and temperature on the adsorption of gases on solids. (i) Adsorption decreases with an increase in temperature since it is an exothermic process by applying Le Chatelier’s principle the reaction... 1
- Why is adsorption always exothermic? When a gas is adsorbed on the surface of a solid, its entropy decreases, i.e., ΔS is negative. Now, ΔG = ΔH-TΔS For a process to be spontane... 1
- What role does adsorption play in heterogeneous catalysis? In heterogenous catalysis, generally the reactants are gaseous whereas catalyst is a solid. The reactant molecules are adsorbed on the surfa... 1
- What is an adsorption isotherm? Describe Freundlich adsorption isotherm. Adsorption isotherm represents the variation of the mass of the gas adsorbed per gram of the adsorbent with pressure at constant temperature... 1
- What are the factors which influence the adsorption of a gas on a solid? The adsorption of a gas on a solid surface is an example of physical adsorption. It is influenced by the following factors : (i) Nature of t... 2
- Give reason why a finely divided substance is more effective as an adsorbent? Finely divided substance has large surface area and hence greater adsorption. 1
- What is the difference between physical adsorption and chemisorption ? Physisorption Chemisorption Weak van der Waals’ forces present. Strong chemical bond forces present. Low; of the order of 20-40 kJ/mol. High... 1
- Distinguish between the meaning of the terms adsorption and absorption. Give one example of each. Adsorption Absorption Substance is concentrated only at the surface and does notpcnctrate from the surface to the bulkofthe adsorbent. Subst... 1
- A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T Torque x = MB sinθ 4.5 × 10⁻² = M (0.25 sin 30°) Magnetic dipole moment, M = 0.36 J T⁻¹. 1
- The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. Earth’s magnetic field gets recorded weakly in certain rocks during their solidification. An analysis of these rocks may reveal the history... 1
- The charged currents in the outer conducting regions of the earth’s core are One of the possibilities is the radioactivity in the interior of the earth. But it is not certain. 1
- The earth’s core is known to contain iron. Yet geologists do not regard this as a source of the earth’s magnetism. Why? The earth’s core does contain iron but in the molten form only. This is not ferromagnetic and hence it cannot be treated as a source of eart... 1
- The earth’s magnetic field varies from point to point in space. Does it also change with time? Yes, earth’s field undergoes a change with time. For example, daily changes, annual changes, secular changes with period of the order of 960... 1
- Geologists claim that besides the main magnetic N-S poles, there are several local poles on the earth’s surface Localised magnetic dipoles can develop due to magnetised mineral deposits or movement of charged ions in atmosphere. 1
- The earth’s field, it is claimed, roughly approximates the field due to a dipole of magnetic moment Let us consider the magnetic field on surface of earth due to assumed bar magnet of dipole moment 8 × 10²² J T⁻¹ located at centre of earth.... 2