Class 12th

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The magnetic moment of an ion is determined by its number of unpaired electrons (n). For the given lanthanide ions:

o Ce? has 0 unpaired electrons (4f? ).

o Eu³? has 6 unpaired electrons (4f? ).

o Gd³? has 7 unpaired electrons (4f? ).
Gd³? has the highest number of unpaired electrons and therefore the highest magnetic moment.

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7 months ago

The solubility of CdSO? in water is 8.0 * 10? mol L?¹. Its solubility in 0.01 M H?SO? solution is ________ * 10? mol L?¹. (Round off to the nearest integer).
(Assume that solubility is much less than 0.01 M)

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Contributor-Level 9

Solubility of CdSO? is water ; S = 8 * 10? M
Using Ksp = S²
Ksp = 64 * 10? M
Now,
CdSO? Cd²? + SO? ²?
in H? SO? (0.01M)
Ksp = [Cd²? ] [SO? ²? ]
64 * 10? = S? (S? + 0.01)
S? << 0.01
So, S? = 64 * 10? M.

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7 months ago

Consider the above reaction where 6.1 g of Benzoic acid is used to get 7.8g of m- bromo benzoic acid. The percentage yield of the product is ________. (Round off to the nearest integer).
[ Given : Atomic masses : C: 12.0u, H:1.0u, O:16.0u, Br:80.0 u]

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Class 12th Chemistry Chemical Kinetics

Contributor-Level 9

Moles of benzoic acid = 6.1 / 121 = 0.05
Theoretical moles of m- bromobenzoic acid = 0.05
Observed moles of m- bromobenzoic acid = 7.8 / 200 = 0.039
% yield = (0.039 / 0.05) * 100 = 78%

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7 months ago

A reaction has a half life of 1 min. The time required for 99.9% completion of the reaction is ________ min. (Round off to the nearest integer).
[Use In 2 = 0.69; In 10 = 2.3]

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Contributor-Level 9

Half life, t? /? = 1min
Let, time of 99.9% completion of reaction be 't' min
Let the reaction is of first order
K = (2.303/t) log? ( [R]? / [R])
[R] = 0.001 [R]?
t = (2.303 * 3 min) / 0.693
t = 9.99 min
the nearest integer is 10.

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7 months ago

In the above reaction, the reagent "A" is:

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Class 12th Chemistry Electrochemistry

Contributor-Level 10

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The molar conductivities at infinite dilution of barium chloride, sulphuric acid and hydrochloric acid are 280, 860 and 426 Scm² mol?¹ respectively. The molar conductivity at infinite dilution of barium sulphate is ________ S cm² mol?¹. (Round off to the nearest integer).

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Contributor-Level 9

λ° (BaCl? ) = 280 Scm²mol? ¹
λ° (H? SO? ) = 860 Scm²mol? ¹
λ° (HCl) = 426 Scm²mol? ¹
λ° (BaSO? ) = λ° (BaCl? ) + λ° (H? SO? ) - 2λ° (HCl)
= 280 + 860 - 2 * 426
= 288 Scm² mol? ¹

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7 months ago

In Tollen's test for aldehyde, the overall number of electron(s) transferred to the Tollen's reagent formula [Ag(NH?)?]? per aldehyde group to form silver mirror is ________. (Round off to the nearest integer).

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Contributor-Level 9

In Tollen's test for aldehyde, aldehyde is oxidized to carboxylic acid salt as:
R – CHO + H? O →R – COO? + 3H? + 2e?
So; 2e? are transferred per aldhyde group.

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7 months ago

Kindly consider the following

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Contributor-Level 10

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7 months ago

A xenon compound 'A' upon partial hydrolysis gives XeO?F?. The number of lone pair of electrons present in compound A is ________. (Round off to the nearest integer).

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Contributor-Level 9

Partial hydrolysis of XeF? gives XeO? F?
XeF? + 2H? O → XeO? F? + 4HF
Compound A is XeF? , so number of lone pair on Xe is 1.

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7 months ago

Which of the following reduction reaction CANNOT be carried out with coke?

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