Page 103 - General Knowledge

GENERAL KNOWLEDGE 2019

 The smallest particle that exhibits the unique chemical characteristics of an element is
known as an atom.
 Atoms are composed of smaller particles known as protons, neutrons, and electrons.
 A proton is a subatomic particle that has significant mass and contributes a single positive
electrical charge to an atom.
 Neutrons also have significant mass, but no electrical charge.

 Electrons are extremely light subatomic particles having a mass that is 1/1840 of a proton.
 Atomic mass number is an atom‘s total number of neutrons and protons.
 Elements can be classified as being either metals, non-metals, or metalloids.
 Metals are elements that usually conduct heat and electricity and are shiny.
 Non-metals do not conduct electricity and are normally not shiny.
 Metalloids have characteristics that are in between metals and nonmetals.
 Elements with a net positive or negative charge are called ions.
 Compounds and molecules constructed in living tissues are commonly called organic.
 Forms of matter not formed by living things are termed inorganic.
 There are four general categories of organic compounds: Lipids, Carbohydrates, Proteins
and Nucleic acids.

Atmosphere
 The atmosphere is the body of air which surrounds our planet.
 Most of our atmosphere is located close to the earth‘s surface where it is most dense.

 The air of our planet is 79 % nitrogen and just under 21% oxygen; the small amount
remaining is composed of carbon dioxide and other gases.
 The greenhouse effect is a naturally occurring process that aids in heating the Earth‘s
surface and atmosphere.
 It results from the fact that certain atmospheric gases, such as carbon dioxide, water vapor
and methane, are able to change the energy balance of the planet by absorbing long wave
radiation emitted from the Earth‘s surface.
Structure of the Atmosphere
 The atmosphere has a layered structure, because of density stratification as a result of
which lighter gases move up and denser ones settle down.
 The lowermost part of the atmosphere in which we live, and which is the theatre for almost
all the weather phenomena is known as the troposphere.
 Troposphere literally means the region of mixing and has been derived from the Greek word
‗Tropos‘, meaning mixing or turbulence.
 The height of the troposphere at the poles is about 8 km, while at the equator it is about 16
km.
 This is because there is greater heating at the equator.
 Above troposphere is the stratosphere, which is important primarily because of the presence
of ozone.
 This layer of calm and clear air is preferred for high-speed jet flights because of the absence
of air pockets.
 Above stratosphere is the mesosphere, which more of a transitional layer.
 Above mesosphere lies the ionosphere, which has electrically conducting layers that help in
radio communication.

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