Chemistry Questions

Q:

The M.K.S. system was first introduced by

A) archimedes B) Eienstein
C) Newton D) Giorgi
 
Answer & Explanation Answer: D) Giorgi

Explanation:
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Q:

Which compound matches the IR Spectrum?

 

spectr1525848245.jpg image

A) 1, 5 – hexadiene B) 3 – Hexanol
C) Trans – 4 – octene D) None of the above
 
Answer & Explanation Answer: A) 1, 5 – hexadiene

Explanation:

3 – Hexanol:


image

There is no alcohol stretch present in the spectrum. Therefore, the above structure is not suitable for the given spectrum.

 

Trans – 4 – octene:


image

There is no vinyl bending present in the spectrum. Therefore, the above structure is not suitable for the given spectrum.


1, 5 – hexadiene:


image

The vinyl bending and other stretches were matched with the above structure.

 

 

Hence, the c = c stretch, vinyl bending and image stretch were matched with the above structure.

Therefore, the given spectrum belongs to 1, 5 – hexadiene.

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Q:

What is the oxidation number of sulfur in H2S?

A) 2 B) -2
C) 1 D) -1
 
Answer & Explanation Answer: B) -2

Explanation:

The sum of the oxidation numbers in a compound must equal zero. In the compound hydrogen sulfide, H2S, the two hydrogen atoms have an oxidation number of +1, for a total of +2.

 What_is_the_oxidation_number_of_sulfur_in_H2S1556279499.jpg image

Therefore, the oxidation number of sulfur in the compound is -2, and the sum of the oxidation numbers is 0.

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Q:

Which one of the following mixture is homogeneous

A) starch and sugar B) methanol and water
C) graphite and charcoal D) calcium carbonate and calcium bicarbonate
 
Answer & Explanation Answer: B) methanol and water

Explanation:
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Q:

Sodium carbonate crystal lose water molecules this property is called

A) hygroscopy B) deliquescence
C) efflorescence D) None of these
 
Answer & Explanation Answer: C) efflorescence

Explanation:
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Q:

Which pair of atoms has the highest electronegativity difference?

 

(Calcium's electronegativity is 1.0

Fluorine's electronegativity is 4.0

Hydrogen's electronegativity is 2.2

Sodium's electronegativity is 0.93)

A) F-F B) Ca-F
C) H-F D) Na-F
 
Answer & Explanation Answer: D) Na-F

Explanation:

F-F = 4 - 4 = 0

Ca-F = 4 - 1 = 3.0

H-F = 4 - 2.2 = 1.8

Na-F = 4 - 0.93 = 3.07

 

Hence, the highest electronegativity difference is in Na-F.

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Q:

Permanent Hardness of water can be removed by adding

A) Bleaching powder B) Chlorine
C) Wasshing soda D) Potassium permanganate
 
Answer & Explanation Answer: C) Wasshing soda

Explanation:

Hardness can be removed by adding sodium carbonate (washing soda) or by passing the water through an ion-exchange column.

 

Hardness in water is caused by dissolved magnesium ions and calcium ions. These can get into the water when it comes into contact with limestone and other rocks that contain calcium compounds. This can happen, for example, when rainwater flows over these rocks on its way to a reservoir.

 

Hardness in water is of two types. They are :

1. Temporary hardness

2. Permanent hardness

 

1. Temporary hardness:: Temporary hardness is caused by dissolved calcium hydrogen carbonate.


2. Permanent hardness:: Permanent hardness is caused by dissolved calcium sulfate. Unlike temporary hardness, it is not removed by boiling the water.

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Q:

The absolute value of charge on electron was determined by

A) J.J.Thomson B) R.A. Millikan
C) Rutherford D) Chadwick
 
Answer & Explanation Answer: B) R.A. Millikan

Explanation:
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