Chemical Reaction and Equation class X - Important questions :

 

Important questions : Chemical Reaction and Equation .  It is most important topic of NCERT  Chemical Reaction and Equation chapter 1  in Class 10.  Questions are frequently asked in the CBSE  board ,   ICSE Board and other competitive exam ( IIT JEE, NEET,  AIMS, State Engineering exam ) from “ Chemical Reaction and Equation “.

Chemical Reaction and Equation question bank will be very beneficial for the students who are engaged in the preparation of  upcoming board exam and other competitive exam .

Chemical Reaction and Equation class 10 – Important Facts

 

Ques-   What color is ferrous oxide ( FeO ) ?

Ans:

* It is a black-colored powder.

 

Ques-   What is the color of ferric oxide  Fe₂O₃?

Ans:    reddish-brown

 

Ques-   What is the colour of Fe₃O₄?

Ans:  

* It is black in colour.

* It is also known as Magnetite or Magnetic oxide.

 

Ques-   What is the difference between Fe₂O₃ and Fe₃O₄?

Ans:

* FeO is a simple oxide where Fe is only + 2 in the oxidation state

* Fe₂O₃ is a simple oxide where Fe is only + 3 in the oxidation state

* Fe₃O₄ is a mixed oxide where Fe is present in both + 2 and + 3 oxidation states.

* Fe₂O₃ is written as iron oxide (III) while Fe₃O₄ is written as iron oxide (II, III).

 

Ques-   What is colour of ferrous sulphate crystal FeSO₄. 7H₂O.  How does this colour change after Heating?

Ans:

* The colour of ferrous sulphate crystal ( FeSO₄. 7H₂O )  is green.

* After heating, the ferrous sulphate crystal , It loses water molecules and forms anhydrous ferrous sulphate  ( FeSO₄ )  , which is white in colour.

* Subsequently, it decomposes to give ferric oxide ( Fe₂O₃ ) , which is brown in colour,  sulphur dioxide and sulphur trioxide.

 

Ques-   What is the Colour of ferrous chloride ( FeCl₂ ) ?

Ans:   greenish white

* Ferrous chloride is a greenish white crystalline solid. It is soluble in water. It is noncombustible.

 

Ques-   What is the colour of CuSO₄. 5H₂O?

Ans:    blue.

 

* CuSO₄.5H₂O is blue in colour .

* Anhydrous  CuSO₄ is colourless.

*  Aqueous solution of  CuSO₄  is Blue.

 

Ques-   What is the colour of CuCl₂?

Ans:     CuCl₂ is green

 

Ques-   What is the colour of Cu₂Cl₂?

Ans:       Cu₂Cl₂ is white.

 

Ques-   What is the Colour of PbSO₄ ?

Ans:      White

* Lead Sulphate (PbSO₄) is a white crystal or powder.

* It is also known as fast white, milk white, sulfuric acid lead salt or anglesite.

 

Ques-   Is PbSO₄ a precipitate?

Ans:  PbSO₄ precipitates  because it is less soluble.

 

Ques-   What is the Colour of PbCl₂?

Ans:     white

 

Ques-   What is the Colour of lead iodide( PbI₂) ?

Ans:      Yellow

 

Ques-   What is the Colour of precipitate of BaSO₄?

Ans:      White

 

Ques-   What is the Colour of Aluminium hydroxide [ Al (OH)₃  ] precipitate?

Ans:    White amorphous powder

 

Some Common Gas

H₂

* Hydrogen is a colorless, odorless, tasteless, and nonpoisonous gas

* You can test for hydrogen gas by putting a burning splinter near the gas. The splinter will gives out a 'pop' sound  if it is hydrogen gas.

 

Cl₂

* Chlorine is a greenish-yellow,  with a sharp smell (the smell of bleach).

* Chlorine kills bacteria – it is a disinfectant.

 

O₂

* It is a colorless, odorless and tasteless gas.

 

N₂

* A colourless, odourless gas.

 

NO

* Nitric oxide appears as a colorless gas.

* It is Noncombustible but accelerates the burning of combustible material.

* Nitric oxide production is essential for overall health because it allows blood, nutrients and oxygen to travel to every part of your body effectively and efficiently.

* NO is neutral oxide.

* Neutral oxides show neither basic nor acidic properties and hence do not form salts when reacted with acids or bases, e.g., carbon monoxide (CO); nitrous oxide (N₂O); nitric oxide (NO), etc., are neutral oxides.

 

NO₂ 

* Nitrogen dioxide (NO₂),  is a reddish-brown gas with a pungent odour.

* Nitric oxide reacts with oxygene or ozone in the air to form nitrogen dioxide.

 

N₂O

* Nitrous oxide is a colorless with a faint, sweet smell.

* Other names :  Laughing gas, sweet air

 

CO₂  

* It is a colorless and odorless gas.

* It is a non-flammable gas.

 

H₂S

* Hydrogen sulphide is a colourless.

* It has a smell that is obnoxiously foul and closely resembles the smell of rotten eggs.

 

SO₂

* Sulfur dioxide is a colorless gas with a pungent odor.