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
Name of the compound | Number of atoms of elements in the molecule | Rule for writing the formula | Formula |
Carbon dioxide | First , then | ||
Carbon monoxide | First , then | ||
Methane | First , then | ||
Ammonia | First , then | ||
Hydrogen sulphide | First , then | ||
............................. | First , then | ||
Hydrogen chloride | First , then |

HARD
6th West Bengal Board
IMPORTANT
Name of the compound | Formula | Explanation |
Carbon dioxide | 2 atoms of , therefore dioxide | |
Phosphorus trichloride | 3 atoms of , therefore trichloride | |
Carbon tetrachloride | 4 atoms of , therefore tetrachloride | |
Phosphorus pentachloride | 5 atoms of , therefore pentachloride | |
Phosphorus .............. | ........................................... | |
Sulphur.............. | 3 atoms of , therefore ................ |

HARD
6th West Bengal Board
IMPORTANT
Name of the compound | Formula | Atoms present in the compound | Number of atoms combined with one atom of the other element |
Water | Oxygen and Hydrogen | ||
Methane | Carbon and Hydrogen | ||
Ammonia | and | ||
Phosphine | and | ||
Hydrogen chloride | and | ||
Hydrogen iodide | and | ||
Hydrogen sulphide | and |

MEDIUM
6th West Bengal Board
IMPORTANT
Element | Symbol | Valency |
Oxygen | ||
Nitrogen | ||
Carbon | ||
Sulphur | ||
Chlorine | ||
Fluorine | ||
Iodine |

MEDIUM
6th West Bengal Board
IMPORTANT
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.
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
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 |
