Short Answer TypePressure is determined as force per unit area of the surface. The SI unit of pressure, pascal is as shown below:
1 Pa = 1N m–2
If mass of air at sea level is 1034 g cm–2, calculate the pressure in pascal.
Express each of the following in SI units:
93 million miles (this is the distance between the earth and the sun)
Express each of the following in SI units:
5 feet 2 inches (the average height of an Indian female).
Long Answer TypeDefine matter. Briefly describe the physical classification (three different stages) of matter.
Describe briefly the chemical classification of matter.
Or
Define the terms element, compound and mixture.
According to chemical classification, matter can be classified into two types:
(i) Pure substances
(ii) Mixtures
(i) Pure substances: A pure substance is made up of one type of substance. It can be further classified into two types:
(a) Elements
(b) Compounds
(a) Elements. An element is defined as pure substance that contains only one kind of atoms. An element has definite physical and chemical properties. For example, hydrogen, phosphorus, iodine and sulphur are all elements. There are 105 elements known at present.
(b) Compounds. A compound is a pure substance containing two or more than two elements combined together in some definite proportion by weight and which can be decomposed into its constituent elements by chemical means. For example, water is a compound formed by the combination of elements hydrogen and oxygen in a fixed proportion, 1 : 8 by weight. Water can also be decomposed into hydrogen and oxygen by passing electricity through it.
(ii) Mixtures. A mixture is made up of two or more than two substances in varying amounts and can be separated into constituents by some suitable physical means. Mixtures are of two types:
(a) Homogenous mixtures
(b) Heterogenous mixtures.
(a) Homogenous mixtures: Homogenous mixtures are the mixtures which have same composition throughout. For example, air is a homogenous mixture of a number of gases like oxygen, nitrogen, CO2 etc. Similarly alloys are homogenous mixtures of metals.
(b) Heterogenous mixtures: Heterogenous mixtures are the mixtures which have different compositions in different parts. For example, a mixture of sand and sugar and a mixutre of sulphur and sand etc.
Switch
