Explanation:
An element is defined as a substance that contains same type of atoms which cannot be broken down into simpler substances.
A compound is defined as a substance that contains more than two different atoms in a fixed ratio by mass. Elements of a compound are chemically combined together.
A homogeneous mixture is defined as a mixture in which solute particles are uniformly distributed into the solvent.
Whereas a heterogeneous mixture is defined as a mixture in which solute particles are non-uniformly distributed in a solvent.
In both homogeneous and heterogeneous mixture there is no chemical combination between solute and solvent particles.
Hence, the given species are classified as follows.
(a) Sea water : It contains decays of dead plants and animals. As a result, these are suspended into the water. Hence, sea water is a heterogeneous mixture.
(b) Helium gas : It contains only atoms of helium. Hence, it is an element.
(c) Sodium chloride (salt) : It is a compound in which sodium and chlorine atoms are present in 1:1 ratio.
(d) A bottle of soft drink : As soft drinks contain a clear solution with no suspended particles. Hence, it is a homogeneous mixture.
(e) a milkshake : It contains different elements which are evenly distributed in the milk. Hence, milk shake is a homogeneous mixture.
(f ) air in a bottle : As air in a bottle will not contain any smoke or fog. So, there will be even distribution of all the gases present in air. Hence, it is a homogeneous mixture.
(g) concrete : It contains cement, fine aggregates, coarse aggregates, water and other particles that are not evenly distributed. Hence, concrete is a heterogeneous mixture.
