Chemistry Questions

Q:

A particle which is similar to electron is

A) positron B) beta particle
C) photon D) mason
 
Answer & Explanation Answer: B) beta particle

Explanation:
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Q:

The magnetic moment (spin only) of  [NiCl4]2-is

A) 1.41 BM B) 1.82 BM
C) 5.46 BM D) 2.82 BM
 
Answer & Explanation Answer: D) 2.82 BM

Explanation:

Hybridisation of Ni is e-  

Unpaired 3d8in  is 2 

So Ω = n(n+2)BM=2x4 = 8 = 2.82BM

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Q:

What are the reactants in a chemical reaction?

Answer

In a chemical reaction, substances (elements or compounds) called reactants are changed into other substances (compounds or elements) called products. Hence, reactants are those which start the chemical reaction.


 


For example:


1. In the burning of natural gas, methane (CH4) and oxygen (O2) are the reactants in the chemical reaction. are the substances formed by a chemical reaction. In the burning of natural gas, carbon dioxide (CO2) and water (H2O) are the products formed by the reaction.


 


2. H2+O2 ----> H2O


Here H2 & O2 are called Reactants and H2O is called Product.


 

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Q:

Which of the following processes is used to remove reducible oxides from the metal?

A) liquation B) cupellation
C) poling D) electro refining
 
Answer & Explanation Answer: C) poling

Explanation:
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Q:

The reactivity of an atom arises from 

A) the existence of unpaired electrons in the valence shell B) the energy differences between the electron shells
C) the sum of the potential energies of all the electron shells D) the average distance of the outermost electron shell from the nucleus
 
Answer & Explanation Answer: A) the existence of unpaired electrons in the valence shell

Explanation:

When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.

 

Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.

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Q:

Order of basicity of amines in gaseous state?

A) 2'> 1'> 3' > NH3 B) 3' > 2' > 1'> NH3
C) 1' > 2' > 3'> NH3 D) 2'> 3'> 1' > NH3
 
Answer & Explanation Answer: B) 3' > 2' > 1'> NH3

Explanation:

The order of basicity in ammonia is different in gaseous phases vs. aqueous phases due to hydrogen bonding.

 

So in gaseous phases it's the well known: 3' > 2' > 1'> NH3. Just so we're on the same page, this is due to the inductive effect of electron donating alkyl groups--they destabilize the lone pair on nitrogen atom, making nitrogen more basic.

 

But in aqueous phase, the order is slightly different: 2'> 1'> 3' > NH3.

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Q:

In photography, the compound of nitrogen used is 

A) Potassium nitrate B) Silver nitrate
C) Ammonium carbonate D) Ammonium bicarbonate
 
Answer & Explanation Answer: B) Silver nitrate

Explanation:

Silver nitrate is the basic substance from which silver bromide is obtained. The photographic films are impregnated with the light sensitive AgBr.

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Q:

Formation of curd from milk is chemical reaction.

A) TRUE B) FALSE
Answer & Explanation Answer: A) TRUE

Explanation:

The process of conversion of milk into curd is called fermentation.  It is a chemical change. Milk consists of globular proteins called casein. As the microorganism lactobacillus react with milk and turn it to curd. For it 37 degree temperature is needed. But sometimes when it does not get favourable condition, then other microorganism react and makes the curd taste different.

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