Question

You can separate a mixture of sand, salt and water by:
(A) Filtration and distillation
(B) Decantation and evaporation
(C) Filtration and decantation
(D) Decantation and crystallization

Answer 1

When two or more different substances are physically mixed together and the identities of the substances mixed are retained, that is they are not changed, it is called as a mixture. Mixtures are combined in the form of solutions, suspensions and colloids.

Complete Step by step solution:
Mixtures are of two types which are homogenous mixtures and heterogeneous mixtures. A homogenous mixture is a type of mixture where substances are uniformly distributed like salt in water. A mixture where substances are not uniformly distributed is known as a heterogenous mixture, like sand in water.
Energy used in forming a mixture is either zero or negligible energy. All the mixtures have a variable composition and not a fixed, defined composition. The properties of the substituents of a mixture remain unchanged, even though combining together.
Mixtures are separable by various physical means such as filtration, evaporation, gravitational sorting, centrifugation, distillation, decantation, crystallization and many others.
Filtration: It is a process in which solid matter and fluid are separated by a filter medium. Through the filter medium, only fluid can pass and it possesses a complex structure.
Distillation: It is the process in which the components and substances from a liquid mixture are separated with the help of selective boiling and condensation.
Evaporation: It is the process in which the liquid is converted into vapour to separate it from the dissolved one or more salts in it.
Decantation: It is the process in which there is separation of mixtures of immiscible liquids or a mixture of a liquid and a solid.
Hence we can separate a mixture of sand, salt and water by decantation and evaporation. Sand can be separated from salt and water by decantation and salt can be separated from water by evaporation.
Therefore, the correct option is B.

Note:
Air is a classic example of a homogenous mixture of gases such as nitrogen, oxygen and little amounts of other substances. Air contains 78 percent nitrogen, 21 percent oxygen, approximately 1 percent argon, etc.