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Element 'B' forms ccp structure and 'A' occupies half of the octahedral voids, while oxygen atoms occupy all the tetrahedral voids. The structure of bimetallic oxide is :
 
Option: 1 A_{4}B_{2}O
Option: 2 AB_{2}O_{4}
Option: 3 A_{2}BO_{4}
Option: 4 A_{2}B_{2}O
 

 

 

Voids -

Voids are empty spaces in a unit cell. They are of four types: triangular, tetrahedral, octahedral, cubic.

-

 

 

 

 

 

 

B forms ccp structure (FCC)

Number of atoms per unit cell of 'B'=\frac{1}{8}\times8+6\times\frac{1}{2}=4

'A' occupies half of the octahedral voids.

Number of atoms of element A:-\; \; \frac{1}{2}\left [ 12\times\frac{1}{4}+1 \right ]

                                                        =\frac{1}{2}\times4=2

'O' atoms occupy all the tetrahedral voids.

Number of atoms of \\O:-\; \; 8

[2 Td voids on 4 Body diagonal]

Structure of bimetallic oxide is :-

A_{2}B_{4}O_{8}=AB_{4}O_{4}

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Posted by

Ritika Jonwal

Mischmetal is an alloy consisting mainly of :
Option: 1 lanthanoid metals
Option: 2 actionoid and transition metals
Option: 3 Lanthanoid and actionoid metals
Option: 4 actionoid metals

Mischmetal is an alloy of lanthanoid metals with Fe.

It consists of a lanthanoid metal (~95%) and iron (~5%) and traces of S, C, Ca, and Al.

Therefore, the correct option is (1).

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Posted by

Kuldeep Maurya

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The incorrect statement(s) among (a)-(c) is (are): (a) W(VI) is more stable than Cr(VI) (b) in the presence of HCl, permaganate titrations provide satisfactory results. (c) some lanthnoid oxides can be used as phosphorous
Option: 1 (b) and (c) only
Option: 2 (a) and (b) only
Option: 3 (b) only
Option: 4 (a) only

(a) W(VI) is more stable than Cr(VI). It is true and given in NCERT.

(b) in the presence of HCl permanganate titrations provide satisfactory results. It is incorrect.

Permanganate titrations in presence of hydrochloric acid are unsatisfactory since hydrochloric acid is oxidised to chlorine.

(c) Some individual Ln oxides are used as phosphors in television screens and similar fluorescing surfaces.

So,(b) is incorrect.

Therefore, the correct option is (3).

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Posted by

Kuldeep Maurya

The reaction white phosphorus on boiling with alkali in inert atmosphere resulted inthe formation of product 'A'. The reaction of 1 mol of 'A' with excess of AgNO_{3} in aqueous medium gives ________mol (s) of Ag. (Round off to the Nearest Integer).
Option: 1 4
Option: 2 -
Option: 3 -
Option: 4 -

The reaction of white phosphorus on boiling with alkali in the inert atmosphere resulted in the formation of the product 'A'.

\mathrm{P}_{4}+3 \mathrm{OH}^{-}+3 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{PH}_{3}+\underset{\text { (A) }}{3 \mathrm{H}_{2} \mathrm{PO}_{2}^{-}}

The reaction 1 mol of 'A' with an excess of AgNO3 in an aqueous medium gives 4 moles of Ag.

\underset{1 \text { mole }}{\mathrm{H}_{2} \mathrm{PO}_{2}^{-}}+\underset{\text { excess }}{4 \mathrm{Ag}^{+}}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow \underset{4 \text { mole }}{4 \mathrm{Ag}\ +\ } \mathrm{H}_{3} \mathrm{PO}_{4}+3 \mathrm{H}^{+}

Ans = 4

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Posted by

Kuldeep Maurya

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One of the by-products formed during the recovery of NH3 from Solvay process is :
Option: 1 NaHCO3
Option: 2 CaCl2
Option: 3 Ca(OH)2
Option: 4 NH4Cl

On a small scale ammonia is obtained from ammonium salts which decompose when treated with caustic soda or calcium hydroxide.

2 \mathrm{NH}_{4} \mathrm{Cl}+\mathrm{Ca}(\mathrm{OH})_{2} \rightarrow 2 \mathrm{NH}_{3}+2 \mathrm{H}_{2} \mathrm{O}+\mathrm{CaCl}_{2}

\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}+2 \mathrm{NaOH} \rightarrow 2 \mathrm{NH}_{3}+2 \mathrm{H}_{2} \mathrm{O}+\mathrm{Na}_{2} \mathrm{SO}_{4}

Recovery of NH3

\begin{aligned}2 \mathrm{NH}_{4} \mathrm{Cl}+\mathrm{Ca}(\mathrm{OH})_{2}\longrightarrow & \mathrm{CaCl}_{2}+2 \mathrm{NH}_{3}+2 \mathrm{H}_{2} \mathrm{O}\\ & \text { byproduct } \end{aligned}

Therefore, the Correct option is (2)

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Posted by

Kuldeep Maurya

The set of elements that differ in mutual relationship from those of the other sets is :
 
Option: 1 B – Si
Option: 2 Li – Mg
Option: 3 Be – Al
Option: 4 Li – Na

Mutual relationships can be anything.

Li–Mg, B–Si, Be–Al show diagonal relationship but Li and Na do not show diagonal relationship as both belongs to the same group and not placed diagonally.

Therefore, the Correct option is (4)

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Posted by

Kuldeep Maurya

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Given below are two statements : Statement I : The E^{o} value for Ce^{4+} / Ce^{3+} is +1.74\; V. Statement II : Ce is more stable in Ce^{4+} state than Ce^{3+} state. In the light of the above statements, choose the most appropriate answer from the options given below :
 
Option: 1 Both statement I and statement II are correct
Option: 2 Both statement I and statement II are incorrect
Option: 3 Statement I is incorrect but statement II is correct  
Option: 4 Statement I is correct but statement II is incorrect

The Eo value for Ce4+/Ce3+ is +1.74 V because the most stable oxidation state of lanthanide series elements is +3.

It means Ce3+ is more stable than Ce4+

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Posted by

Kuldeep Maurya

A group 15 element, which is a metal and forms a hydride with strongest reducing power among group 15 hydrides. The element is :
 
Option: 1 Bi
Option: 2 As
Option: 3 Sb
Option: 4 P

N, P are Non-Metal

As, Sb are Metalloid

Bi is Metal

Hydrides of group 15 elements are

NH3 , PH3 , AsH3 , SbH3 , BiH3

In NH3, the hydrogen atom gets a partial positive charge due to less electronegativity. But in BiH3, the hydrogen atom gets a partial negative charge because hydrogen is more electronegative than bismuth.

 BiH3 is a strong reducing agent than others because we know that H- is a strong reducing agent and Bi – H bond dissociation energy is very less.

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Posted by

Kuldeep Maurya

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Given below are two statements : Statement I : Both CaCl2.6H2O and MgCl2.8H2O  undergo dehydrationon heating. Statement II : BeO is amphoteric whereas the oxides of other elements in the same group are acidic. In the light of the above statements, choose the correct answer from the options given below :
Option: 1 Statement I is false but statement II is true
Option: 2 Both statement I and Statement II are false
Option: 3 Statement I is true but statement II is false  
Option: 4 Both statement I and Statement II are true

\text { (a) } \mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O} \stackrel{\Delta}{\longrightarrow} \underset{\text { (Anhydrous) }}{\mathrm{CaCl}_{2}}+6 \mathrm{H}_{2} \mathrm{O}

\text { (b) } \mathrm{MgCl}_{2} .8 \mathrm{H}_{2} \mathrm{O} \stackrel{\Delta}{\longrightarrow} \mathrm{MgO}+2 \mathrm{HCl}+6 \mathrm{H}_{2} \mathrm{O}

The dehydration of hydrated chloride of calcium can be achieved. The corresponding hydrated chloride of magnesium on heating suffer hydrolysis.

\text { (c) } \mathrm{BeO} \rightarrow \text { Amphoteric }

MgO, CaO, SrO, BaO All are basic oxides.

So, Both Statement I and Statement II are false

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Posted by

Kuldeep Maurya

Assertaion and Reasoning question: (i) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A). (ii) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A). (iii) Assertion (A) is correct, but Reason (R) is incorrect statement. (iv) Assertion (A) is incorrect, but Reason (R) is correct statement.  Assertion (A) : F – F bond in F2 molecule is weak. Reason (R) : F atom is small in size
 

(ii) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).

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Posted by

Safeer PP

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