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In the extraction of \(\mathrm{Ca}\) by electro reduction of molten \(\mathrm{CaCl}_{2}\) some \(\mathrm{CaF}_{2}\) is added to the electrolyte for the following reason:

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The reaction for obtaining the metal (M) from its oxide \(\left(\mathrm{M}_{2} \mathrm{O}_{3}\right)\) ore is given by \(\mathrm{M}_{2} \mathrm{O}_{3}(\mathrm{~s})+2 \mathrm{Al}(\ell) \stackrel{\mathrm{Heat}}{\longrightarrow} \mathrm{Al}_{2} \mathrm{O}_{3}(\ell)+2 \mathrm{M}(\mathrm{s}),(\mathrm{s}=\) solid, \(\ell=\) liquid \()\) in that case, \(M\) is

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To a solution of a colourless efflorescent sodium salt, when dilute acid is added, a colourless gas is evolved along with formation of a white precipitate. Acidified dichromate solution turns green when the colourless gas is passed through it. The sodium salt is

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Bond order of \(\mathrm{He}_{2}, \mathrm{He}_{2}^{+}\)and \(\mathrm{He}_{2}^{2+}\) are respectively:

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What will be the mass of one atom of \({ }^{12} \mathrm{C}\) ?

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Which of the following has the largest number of atoms?

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The difference between orbital angular momentum of an electron in a 4 f orbital and another electron in a 4 s orbital is

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How and why does the density of liquid water change on prolonged electrolysis?

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The number of unpaired electrons in the uranium \(\left({ }_{92} \mathrm{U}\right)\) atom is:

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Which of the following statements is not true for the reaction \(2 \mathrm{~F}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 4 \mathrm{HF}+\mathrm{O}_{2} ?\)

asked Dec 11, 2021 in Some basic concepts in chemistry by kritika (90.1k points)

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The radius of the first Bohr orbit of a hydrogen atom is \(0.53 \times 10^{-8} \mathrm{~cm}\). The velocity of the electron in the first Bohr orbit is

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\(\mathrm{K}_{\mathrm{t}}\) (water) \(=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\). The temperature at which ice begins to separate from a mixture of 10 mass \(\%\) ethylene glycol is

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An ideal gas expands adiabatically against vaccum. Which of the following is correct for the given process? (A) \(\Delta S=0\)

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Equal masses of ethane and hydrogen are mixed in a empty container at \(298 \mathrm{~K}\). The fraction of total pressure exerted by hydrogen is

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At \(273 \mathrm{~K}\) temperature and \(76 \mathrm{~cm} \mathrm{Hg}\) pressure, the density of a gas is \(1.964 \mathrm{gL}^{-1}\). The gas is

asked Dec 11, 2021 in Some basic concepts in chemistry by kritika (90.1k points)

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\(5 \mathrm{ml}\) of \(0.1 \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\) is mixed with \(10 \mathrm{ml}\) of \(0.02 \mathrm{M} \mathrm{KI}\). The amount of Pbl \(_{2}\) precipitated will be about

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The mole fraction of ethanol in water is \(0.08\). Its molality is

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Among the following, the ion which will be more effective for flocculation of \(\mathrm{Fe}(\mathrm{OH})_{3}\) sol. is

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The equilibrium constant for the following reactions are given at \(25^{\circ} \mathrm{C}\) $$ \begin{aligned} &2 A \rightleftharpoons B+C, K_{1}=1.0 \\ &2 B \rightleftharpoons C+D, K_{2}=16 \\ &2 C+D \rightleftharpoons 2 P, K_{3}=25 \end{aligned} $$ The equilibrium constant for the reaction \(\mathrm{P} \rightleftharpoons \mathrm{A}+\frac{1}{2} \mathrm{~B}\) at \(25^{\circ} \mathrm{C}\) is

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In the face-centred cubic lattice structure of gold the closest distance between gold atoms is 'a' being the edge ength of the cubic unit cell

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