MEDIUM
6th West Bengal Board
IMPORTANT
Earn 100

Find the formula of the molecules and complete the table.
Name of the element Number of atoms present in a molecule of the element Formula of the molecule of the element
Oxygen                               2
Nitrogen                               2  
Chlorine                               2  
Iodine                               2  
Fluorine                               2  

 

Important Questions on Element, Compound and Mixture

HARD
6th West Bengal Board
IMPORTANT
Write the formula for the given compounds.
Name of the compound Number of atoms of elements in the molecule Rule for writing the formula Formula
Carbon dioxide C-1; O-2 First C, then O CO2
Carbon monoxide C-1; O-1 First C, then O  
Methane C-1; H-4 First C, then H  
Ammonia N-1; H-3 First N, then H NH3
Hydrogen sulphide H-2; S-1 First H, then S  
............................. S-1; O-2 First S, then O  
Hydrogen chloride H-1; Cl-1 First H, then Cl  

 

HARD
6th West Bengal Board
IMPORTANT
Complete the given table by using the formula.
Name of the compound Formula Explanation
Carbon dioxide CO2 2 atoms of O, therefore dioxide
Phosphorus trichloride PCl3 3 atoms of Cl, therefore trichloride
Carbon tetrachloride CCl4 4 atoms of Cl, therefore tetrachloride
Phosphorus pentachloride PCl5 5 atoms of Cl, therefore pentachloride
Phosphorus .............. PF3 ...........................................
Sulphur.............. SO3 3 atoms of O, therefore ................

 

HARD
6th West Bengal Board
IMPORTANT
Complete the given table.
Name of the compound Formula Atoms present in the compound Number of H atoms combined with one atom of the other element
Water H2O Oxygen and Hydrogen                                  2
Methane CH4 Carbon and Hydrogen  
Ammonia NH3 N and H  
Phosphine PH3 P and H  
Hydrogen chloride HCl H and Cl  
Hydrogen iodide HI H and I  
Hydrogen sulphide H2S H and S  

 

MEDIUM
6th West Bengal Board
IMPORTANT
write valency for the given elements.
     Element    Symbol         Valency
Oxygen             O   
Nitrogen             N  
Carbon             C  
Sulphur             S  
Chlorine            Cl  
Fluorine             F  
Iodine             I  

 

MEDIUM
6th West Bengal Board
IMPORTANT
Write the names of solute and solvent of the solutions mentioned below:
Solution Solute Solvent
Syrup of sugar    
Salt solution    

 

MEDIUM
6th West Bengal Board
IMPORTANT

Examples of some known solutions are given below. Discuss among yourselves and write the name of the compounds of such solutions.

Solutions Components
Salt solution  
Sugar solution  
Lime water  
Air  

 

HARD
6th West Bengal Board
IMPORTANT

Take a little muddy water. Fold a circular filter paper into four folds as shown in the picture. Open one fold and put the cone-shaped paper in a funnel, use a few drops of water to set it properly. Then pour muddy water slowly with the help of a glass rod on the filter paper.

Question Image

Write in the following table what you see after a few minutes:

What you see Why do you think it happens?
   

 

HARD
6th West Bengal Board
IMPORTANT
Complete the following table.
Which solution Size of a solid particle, smaller or greater than that of the pores of the filter paper Which process- simple distillation or filtration - can be used for separation
Muddy water    
Saline water