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10 months ago

Class 12th Chemistry

An aqueous solution of NiCl₂ was heated with excess sodium cyanide in presence of strong oxidizing agent to form ${[N i {(C N)}_{6}]}^{2 -} .$ The total change in number of unpaired electrons on metal centre is_________.

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Vishal Baghel

Contributor-Level 10

$N i C l_{2} + N a C N \to_{O . A .}^{s t r o n g} {[N i {(C N)}_{6}]}^{2 -}$

Complex has Ni⁴⁺ and strong ligand, hence following are the metal ion electronic configuration

Change of unpaired electron = 2

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10 months ago

Class 12th Chemistry

100ml of 0.0018% (w/v) solution of Cl^- ion was the minimum concentration of Cl^- required to precipitate a negative sol in one h. THE coagulating value of Cl^- ion is_________.

(Nearest integer)

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Vishal Baghel

Contributor-Level 10

Wt of Cl^- in 100 ml = 1.8 * 10^-3 gm

Mol. of Cl^- in 100 ml = $\frac{1.8 * 1 0^{- 3}}{35.5} = 0.0507 * 1 0^{- 3} m o l e$

$∴ [C l^{-}] = \frac{0.0507 * 1 0^{- 3} * 1000}{100} = 5.07 * 1 0^{- 4} M$

i.e. 0.507 milli mole in one lit required in one hr.

Coagulation value = (millimole/lit) required in one hr = 0.507

= 1 (the nearest integer)

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10 months ago

Class 12th Chemistry

The wavelength of electrons accelerated from rest through a potential difference of 40 kV is x * 10^-12m. The value of x is________. (Nearest Integer)

Given : Mass of electron = 9.1 * 10^-31kg

Charge on an electron = 1.6 * 10^-19C

Planck's constant = 6.63 * 10^-34Js

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Vishal Baghel

Contributor-Level 10

Here, $λ = \frac{h}{\sqrt[]{2 * m * e V}} = \frac{6.63 * 1 0^{- 34}}{\sqrt[]{2 * 1.6 * 1 0^{- 19} * 40000 * 9.1 * 1 0^{- 31}}} m$

$∴ λ = 0.614 * 1 0^{- 11} m$

$λ = 6.14 * 1 0^{- 12} m$ [the nearest integer = 6]

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New answer posted

10 months ago

Class 12th Chemistry

When 0.15g of an organic compound was analyzed using carius method for estimation of bromine, 0.2397g of AgBr was obtained. The percentage of bromine in the organic compound is_________. (Nearest Integer) (Atomic mass: Ag = 108, Br = 80)

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