Chemistry Questions

Q:

The electrochemical cell stops working after some time because ________

A) Electrode potential of both the electrodes becomes zero B) One of electrodes completely vanishes
C) Electrode potential of both electrodes equalizes D) The reaction reverses its direction
 
Answer & Explanation Answer: C) Electrode potential of both electrodes equalizes

Explanation:
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Q:

The credit for the discovery of transuranic element goes to

A) Hahn B) Rutherford
C) Seaborg D) Curie
 
Answer & Explanation Answer: C) Seaborg

Explanation:
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Q:

Temporary hardness is due to the presence of 

A) Calcium carbonate B) calcium bicarbonate
C) magnesium sulphate D) calcium sulphate
 
Answer & Explanation Answer: B) calcium bicarbonate

Explanation:

Temporary hardness is due to the presence of soluble bicarbonates of calcium and magnesium in water. Permanent hardness is due to the presence of sulphates and chlorides of calcium and magnesium.

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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:

In known elements, the maximum number is of

A) Metals B) Non Metals
C) Metalloids D) None of these
 
Answer & Explanation Answer: A) Metals

Explanation:
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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:

In nuclear reactor,Chain reaction is controlled by introducing

A) cadmium rod B) iron rod
C) platinum rod D) graphite rod
 
Answer & Explanation Answer: A) cadmium rod

Explanation:
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15 7956
Q:

SI unit of equivalent conductance

A) ohm/cm B) Siemens m2/equivalent
C) Siemens/equivalent D) mho/cm
 
Answer & Explanation Answer: B) Siemens m2/equivalent

Explanation:

Equivalent conductance is defined as the conductance of an electrolyte solution containing one gram equivalent of the electrolyte. It is equal to the product of specific conductance (k) of the solution and the volume (V) of the solution that contains one gram equivalent of the electrolyte.

 

 λ = k x V

 

Unit of spceific conductance k is Siemens / m.

Volume of the solution V is m3

Now, required equivalent conductance unit is Siemens.m2/equivalent .

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