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 CO 2 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 NH 3 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

Number of atoms present in a molecule of an element is called atomicity of that molecule. 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 CO 2 Carbon monoxide C - 1 ; O - 1 First C , then O CO Methane C - 1 ; H - 4 First C , then H CH 4 Ammonia N - 1 ; H - 3 First N , then H NH 3 Hydrogen sulphide H - 2 ; S - 1 First H , then S H 2 S Sulphur dioxide S - 1 ; O - 2 First S , then O SO 2 Hydrogen chloride H - 1 ; Cl - 1 First H , then Cl HCl

Complete the given table by using the formula. Name of the compound Formula Explanation Carbon dioxide CO 2 2 atoms of O , therefore dioxide Phosphorus trichloride PCl 3 3 atoms of Cl , therefore trichloride Carbon tetrachloride CCl 4 4 atoms of Cl , therefore tetrachloride Phosphorus pentachloride PCl 5 5 atoms of Cl , therefore pentachloride Phosphorus .............. PF 3 ........................................... Sulphur.............. SO 3 3 atoms of O , therefore ................

The molecule of a compound contains more than one atom of an element, we use Greek prefixes like Di-, Tri-, Tetra- and penta-, etc to indicate. Name of the compound Formula Explanation Carbon dioxide CO 2 2 atoms of O , therefore dioxide. Phosphorus trichloride PCl 3 3 atoms of Cl , therefore trichloride. Carbon tetrachloride CCl 4 4 atoms of Cl , therefore tetrachloride. Phosphorus pentachloride PCl 5 5 atoms of Cl , therefore pentachloride. Phosphorus trifluoride PF 3 3 atoms of F , therefore trifluoride. Sulphur trioxide SO 3 3 atoms of O , therefore trioxide.

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 H 2 O Oxygen and Hydrogen 2 Methane CH 4 Carbon and Hydrogen Ammonia NH 3 N and H Phosphine PH 3 P and H Hydrogen chloride HCl H and Cl Hydrogen iodide HI H and I Hydrogen sulphide H 2 S H and S

The different elements combine separately with different number of hydrogen atoms to form various compounds. Name of the compound Formula Atoms present in the compound Number of H atoms combined with one atom of the other element Water H 2 O Oxygen and Hydrogen 2 Methane CH 4 Carbon and Hydrogen 4 Ammonia NH 3 N and H 3 Phosphine PH 3 P and H 3 Hydrogen chloride HCl H and Cl 1 Hydrogen iodide HI H and I 1 Hydrogen sulphide H 2 S H and S 2

write valency for the given elements. Element Symbol Valency Oxygen O Nitrogen N Carbon C Sulphur S Chlorine Cl Fluorine F Iodine I

The combining capacity of an element is called its valency. The number of hydrogen atoms that combine with one atom of an element to form a compound is called the valency of that element. Element Symbol Valency Oxygen O 2 Nitrogen N 3 Carbon C 4 Sulphur S 2 Chlorine Cl 1 Fluorine F 1 Iodine I 1

Write the names of solute and solvent of the solutions mentioned below: Solution Solute Solvent Syrup of sugar Salt solution

The substance which is dissolved is called the solute and the substance in which it dissolves is called the solvent. In syrup, solid acts as a solute while liquid acts as a solvent. Solution Solute Solvent Syrup of sugar sugar water Salt solution salt water

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

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 The size of solid particles is greater than that of the pores of the filter paper. Filtration. Saline water The size of solid particles is smaller than that of the pores of the filter paper. Simple distillation

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

HARD

6th West Bengal Board

IMPORTANT

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 9

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 $O$	${CO}_{2}$
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 $H$	${NH}_{3}$
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

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 10

Complete the given table by using the formula.

Name of the compound	Formula	Explanation
Carbon dioxide	${CO}_{2}$	2 atoms of $O$ , therefore dioxide
Phosphorus trichloride	${PCl}_{3}$	3 atoms of $Cl$ , therefore trichloride
Carbon tetrachloride	${CCl}_{4}$	4 atoms of $Cl$ , therefore tetrachloride
Phosphorus pentachloride	${PCl}_{5}$	5 atoms of $Cl$ , therefore pentachloride
Phosphorus ..............	${PF}_{3}$	...........................................
Sulphur..............	${SO}_{3}$	3 atoms of $O$ , therefore ................

HARD

6th West Bengal Board

IMPORTANT

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 11

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	$H_{2} O$	Oxygen and Hydrogen	$2$
Methane	${CH}_{4}$	Carbon and Hydrogen
Ammonia	${NH}_{3}$	$N$ and $H$
Phosphine	${PH}_{3}$	$P$ and $H$
Hydrogen chloride	$HCl$	$H$ and $Cl$
Hydrogen iodide	$HI$	$H$ and $I$
Hydrogen sulphide	$H_{2} S$	$H$ and $S$

MEDIUM

6th West Bengal Board

IMPORTANT

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 12

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

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 13

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

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 14

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

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Do it yourself

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

Environment and Science Class 6>Chapter 3 - Element, Compound and Mixture>Exercise 16

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

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

Learn and Prepare for any exam you want !

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

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

Learn and Prepare for any exam you want !

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