Q.10 Briefly
describe sulphur cycle. (AKTU. - 2010 - 11)
Ans. The
sulphur cycle describes the cycle movement of
sulphur through various components of the environment. A large portion
of earth’s sulphur is stored in underground rocks and minerals.
Such as
sulphur salts found buried deep in oceans. Natural sources of sulphur include
volcanic eruptions and organic matter in swamps. Which release sulphurous gases
such as hydrogen sulphide (H2S) and solphur dioxide (SO2). The sulphur ions
present in the atmosphere are utilized by plants and are incorporated in many
essential proteins. The SO2 present in the atmosphere is converted into
sulphur trioxide gas (SO3) and also to tiny droplets of sulphuric
acid (H2SO4), which fall to the earth along with rain. This phenomenon is
known as acid rain and is harmful to standing crops, buildings and monuments,
plants and animals, human beings, and aquatic organisms.
Q.11. Define energy and its different types.
Ans. Energy: -
Energy is a crucial input in the process
of economic social and industrial development. Energy plays a vital role in our
present day life. The degree of development and civilization of a country is
measured by the utilization of energy by human beings for their needs.
Types
of Energy: -
(i) Mechanical Energy (ii) Electrical
Energy
(iii) Chemical Energy (iv) Nuclear
Energy
(v) Hydro Energy
(i)
Mechanical Energy: -
Mechanical energy is in two
forms: Kinetic energy and potential energy.
The
kinetic energy of a moving body is measured by the amount of work which has
been done in bringing the body from rest position to its present position and
vice-versa.
Kinetic energy is given by,
Where m =
mass of body (kg.), v = velocity of body (m/s)
Unit of
K.E. is joule.
The energy
in a body due to its position is called potential energy. Potential energy is
given by
P.E. = mgh
Where m =
mass of body (kg), g = acceleration due to gravity = 9.81 m/s2, h = distance of
fall of body (m)
(ii)
Electrical Energy: -
In generator mechanical energy
converts into electrical energy, fuel cells convert chemical energy into
electrical energy.
The energy required to transfer
the charge W = VQ
\ Power = VI
Unit of
power is watt (W).
(iii)
Chemical Energy: -
In fuel cells, batteries etc.
chemical energy is converted into electrical energy. Also during combustion of
fuel (like coal), the atoms – carbon, hydrogen etc. combine with oxygen with
liberation of heat.
Unit of heat is calorie.
(iv)
Nuclear Energy: -
Uranium, plutonium and thorium
isotopes are nuclear fuels. In their nuclei, the energy is released in the form
of heat by nuclear fission chain reaction. Nuclear Fusion is combining of
nuclei accompanied by release of heat.
If a U235 atom is bombarded by a neutron, the nucleus
splits to give nuclei of other elements.
U235 +
neutron = lanthanum148 + Bromine85 + 3 Free electrons
One
fission of U235 causes a release of 200MeV
of energy.
(v)
Hydro Energy: -
When water drops through a
height, then its energy rotates the turbines which are coupled with alternator,
which delivers the electrical energy. The electric power is given by
