Understanding Matter - 1 (Class IX)

A solution is defined as a homogeneous mixture of two or more chemically non–reacting substances whose composition can be varied within limits. If a mixture is to be called a solution, it must satisfy the following two conditions:
(i) The components of a mixture should be non-reacting.
(ii) Mixture should be homogeneous.
In a mixture of salt and water, salt and water do not react with each other. Moreover, there is homogeneity at the particle level, i.e. it tastes the same throughout. Thus, it is a solution. Mixture of starch and water and mixture of oil in water and mixture of sand and water are heterogeneous mixtures as they have non–uniform composition. Thus, they are not solutions.

A mixture is a material which contains two or more different kinds of particles (atoms or molecules), which are physically mixed in any proportion, but not chemically combined. Tea is a mixture containing water, sugar, salt, milk and tea leaves mixed in different proportions.

A solution is defined as a homogeneous mixture of two or more chemically non–reacting substances whose composition can be varied within limits. If a mixture is to be called a solution, it must satisfy the following two conditions:
(i) The components of a mixture should be non–reacting.
(ii) Mixture should be homogeneous.

Mixture of copper sulphate and water, mixture of potassium permanganate and water and vinegar (mixture of acetic acid and water) are homogeneous mixtures as they have uniform compositions and the components of these mixtures are not visible to the naked eye or even under a microscope. 

A mixture is a material, which consists of two or more pure substances (elements or compounds) which are not chemically combined but physically mixed in any proportion. A mixture shows the properties of all its constituents and it can be reported into its constituents by physical method. Air is a homogeneous mixture of many gases like nitrogen (78%), oxygen (21%), carbon dioxide, inert gases and water vapours. Air is a mixture because its properties are in between those of its constituents. The two major components of air are oxygen and nitrogen. In the presence of oxygen, any fuel burns brightly but in nitrogen it gets extinguished. In contrast, in air, the fuel burns slowly. The components of air can be separated by fractional distillation; moreover the composition of air is also variable. Thus, air is a mixture. An element is a pure substance that contains only one kind of atoms. A molecule is a group of two or more atoms, which are held together strongly by some kind of attractive force. For e.g. H₂, Cl₂, Br₂, etc. A compound is made up of two or more elements chemically combined in fixed proportion by mass. For e.g. H₂O, HCl, NH₃, etc.

A mixture is a material, which consists of two or more pure substances (elements or compounds) which are not chemically combined but physically mixed in any proportion. The mixture shows the properties of all its constituents and it can be separated into its constituents by using physical method. Air is a homogeneous mixture of many gases like nitrogen (78%), oxygen (21%), carbon dioxide, inert gases and water vapours.
Copper suphate, sodium chloride and water are compounds as they are made up of two or more elements chemically combined in a fixed ratio by mass. Therefore, they have definite compositions.

A colloidal solution is a heterogeneous mixture in which the size of the particle is in the range of 1-100 nm in diameter. Due to the small size of particles, these mixtures appear to be homogeneous, but actually they are heterogeneous. Moreover, the colloidal particles pass through ordinary filter paper. Hence, they cannot be separated by filtration. The colloidal particles are not visible to the naked eye. However, in some cases, they are visible under ultramicroscope. So, only option (3), i.e. a colloid is a homogeneous mixture, is an incorrect statement about colloids. 

It is a homogeneous mixture. Homogeneous mixtures have uniform composition throughout the solution.

True solutions do not show Tyndall effect.

Suspensions are heterogeneous mixtures (i.e. having a non-uniform composition) in which particle size is more than 100 nm. Due to large size of particles, they do not pass through the pores of a filter paper and hence, can be easily separated by filtration.  

In Chemistry, a mixture is a material system made up of two or more different substances which are mixed but are not combined chemically. Mixture refers to the physical combination of two or more substances, the identities of which are retained and are mixed in the form of alloys, solutions, suspensions and colloids.

Air is an example of homogeneous mixture.

In ammonia, the ratio of elements is always fixed. This is because ammonia is a compound.

An element is the basic form of a pure substance that contains only a single type of atoms. For example, copper is made up of only a single type of atoms called copper atoms. Therefore, copper is an element. 

A pure substance is defined as one which contains only one kind of atoms or molecules. Based upon the nature of constituent particles, it is of two types, i.e. elements and compounds.