Change the. Following sentences into. Passive
A. The boys are playing. Cricket
Answers
Explanation:
2 CHEMISTRY
Other cultures – especially the Chinese and
the Indian – had their own alchemical traditions.
These included much knowledge of chemical
processes and techniques.
In ancient India, chemistry was called
Rasayan Shastra, Rastantra, Ras Kriya or
Rasvidya. It included metallurgy, medicine,
manufacture of cosmetics, glass, dyes, etc.
Systematic excavations at Mohenjodaro in
Sindh and Harappa in Punjab prove that the
story of development of chemistry in India is
very old. Archaeological findings show that
baked bricks were used in construction work.
It shows the mass production of pottery, which
can be regarded as the earliest chemical process,
in which materials were mixed, moulded and
subjected to heat by using fire to achieve
desirable qualities. Remains of glazed pottery
have been found in Mohenjodaro. Gypsum
cement has been used in the construction work.
It contains lime, sand and traces of CaCO3.
Harappans made faience, a sort of glass which
was used in ornaments. They melted and forged
a variety of objects from metals, such as lead,
silver, gold and copper. They improved the
hardness of copper for making artefacts by
using tin and arsenic. A number of glass objects
were found in Maski in South India (1000–900
BCE), and Hastinapur and Taxila in North
India (1000–200 BCE). Glass and glazes were
coloured by addition of colouring agents like
metal oxides.
Copper metallurgy in India dates back to
the beginning of chalcolithic cultures in the
subcontinent. There are much archeological
evidences to support the view that technologies
for extraction of copper and iron were developed
indigenously.
According to Rigveda, tanning of leather
and dying of cotton were practised during
1000–400 BCE. The golden gloss of the black
polished ware of northen India could not be
replicated and is still a chemical mystery. These
wares indicate the mastery with which kiln
temperatures could be controlled. Kautilya’s
Arthashastra describes the production of salt
from sea.
A vast number of statements and material
described in the ancient Vedic literature can
be shown to agree with modern scientific
findings. Copper utensils, iron, gold, silver
ornaments and terracotta discs and painted
grey pottery have been found in many
archaeological sites in north India. Sushruta
Samhita explains the importance of Alkalies.
The Charaka Samhita mentions ancient
indians who knew how to prepare sulphuric
acid, nitric acid and oxides of copper, tin and
zinc; the sulphates of copper, zinc and iron and
the carbonates of lead and iron.
Rasopanishada describes the preparation
of gunpowder mixture. Tamil texts also
describe the preparation of fireworks using
sulphur, charcoal, saltpetre (i.e., potassium
nitrate), mercury, camphor, etc.
Nagarjuna was a great Indian scientist. He
was a reputed chemist, an alchemist and a
metallurgist. His work Rasratnakar deals with
the formulation of mercury compounds. He has
also discussed methods for the extraction of
metals, like gold, silver, tin and copper. A book,
Rsarnavam, appeared around 800 CE. It
discusses the uses of various furnaces, ovens
and crucibles for different purposes. It
describes methods by which metals could be
identified by flame colour.
Chakrapani discovered mercury sulphide.
The credit for inventing soap also goes to him.
He used mustard oil and some alkalies as
ingredients for making soap. Indians began
making soaps in the 18th century CE. Oil of
Eranda and seeds of Mahua plant and calcium
carbonate were used for making soap.
The paintings found on the walls of Ajanta
and Ellora, which look fresh even after ages,
testify to a high level of science achieved in
ancient India. Varähmihir’s Brihat Samhita is
a sort of encyclopaedia, which was composed
in the sixth century CE. It informs about the
preparation of glutinous material to be applied
on walls and roofs of houses and temples. It
was prepared entirely from extracts of various
plants, fruits, seeds and barks, which were
concentrated by boiling, and then, treated with
various resins. It will be interesting to test such
materials scientifically and assess them for use.
Answer:
cricket is been played by the boys.
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