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Q:

Which one of the following orders presents the correct sequence of the increasing basic nature of the given oxides?

(1) K2O<Na2O<Al2O3<MgO

(2) Al2O3<MgO<Na2O<K2O

(3) MgO<K2O<Al2O3<Na2O

(4) Na2O<K2O<MgO<Al2O3

A) Option 1 B) Option 2
C) Option 3 D) Option 4
 
Answer & Explanation Answer: B) Option 2

Explanation:

While moving from left to right in periodic table basic character of oxide of elements will decrease.

  Increasing basic strengthAl2O3<MgO<Na2O 

 

and while descending in the group basic character of corresponding oxides increases. 

 Increasing basic strengthNa2O<K2O

 

 Correct Order is Al2O3 < MgO <Na2O <K2O

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Q:

Boron cannot form which one of the following anions?

(1) BO2-

(2) BF63-

(3) BH4-

(4) B(OH)4-

A) Option 1 B) Option 2
C) Option 3 D) Option 4
 
Answer & Explanation Answer: B) Option 2

Explanation:

Due to absence of low lying vacant d orbital in B, sp3d2hybridization is not possible hence BF63-will not formed. 

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Q:

Among the following the maximum covalent character is shown by the compound

(1)MgCl2

(2)FeCl2

(3)SnCl2

(4) AlCl3

A) Option 1 B) Option 2
C) Option 3 D) Option 4
 
Answer & Explanation Answer: D) Option 4

Explanation:

According to Fajans rule, cation with greater charge and smaller size favours covalency.

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Q:

The reduction potential of hydrogen half-cell will be negative if :
(1) PH2= 2 atm and [H+] = 2.0 M
(2) PH2= 1 atm and [H+] = 2.0 M
(3) PH2= 1 atm and [H+] = 1.0 M
(4) PH2= 2 atm and [H+] = 1.0 M

A) Option 1 B) Option 2
C) Option 3 D) Option 4
 
Answer & Explanation Answer: D) Option 4

Explanation:

 H+-e-12H2   

Apply Nernst equation  

 

E=0-0.0591logPH212H+  

 

 E=-0.0591log2121  

 

Therefore E is Negative

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Q:

Trichloroacetaldehyde was subject to Cannizzaro's reaction by using NaOH. The mixture of the products contains sodium trichloroacetate and another compound. The other compound is :

A) Chloroform B) 2, 2, 2-Trichloroethanol
C) Trichloromethanol D) 2, 2, 2-Trichloropropanol
 
Answer & Explanation Answer: B) 2, 2, 2-Trichloroethanol

Explanation:

Cl|Cl-C-CHO|ClCannizzaro's ReactionNaOH Cl|Cl-C-COONa|Cl+ Cl|Cl-C-CH2 |21Cl-OH

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Q:

Silver Mirror test is given by which one of the following compounds?

1. Benzophenone

2. Acetaldehyde

3. Acetone

4. Formaldehyde

A) Only 1 B) Only 2
C) 1 and 3 D) 2 and 4
 
Answer & Explanation Answer: D) 2 and 4

Explanation:

Both Formaldehyde and Acetaldehyde will give this test

 HCHO[Ag(NH3)2+]    Silver mirrorAg + Organic compound

 CH3-CHO [Ag(NH3)2+] AgSilver mirror+ Organic compound 

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Q:

The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm3 at 27°C is to a volume of 100 dm3

 

A) 42.3 J/ mole / K B) 38.3 J/ mole / K
C) 35.8 J/ mole / K D) 32.3 J/ mole / K
 
Answer & Explanation Answer: B) 38.3 J/ mole / K

Explanation:

s=nRlnv2v1 

=2.303 nR logv2v1 = 2.303×2×8.314×log10010 = 38.3 J mol-1k-1

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Q:

A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at :

A) 518 nm B) 1035 nm
C) 325 nm D) 743 nm
 
Answer & Explanation Answer: D) 743 nm

Explanation:

1λ=1λ1+1λ2

1355=1680+1λ2

1λ2=680-355680×355

λ2=743nm.

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