The carbon cycle ensures that
the percentage of carbon dioxide in air is kept almost constant
air always contains a constant proportion of oxygen
sufficient amounts of carbohydrates are produced
the process of photosynthesis proceeds smoothly
Correct Answer :
A. the percentage of carbon dioxide in air is kept almost constant
Related Questions
The human body contains about
50% water
10% water
70% water
20% water
The presence of dust particles in air serves
as a nucleus to condense water vapour resulting in rain
to maintain the average density of air
to minimise the inflammatory nature of oxygen
to protect the inhabitants of the earth from the effects of ultra violet rays.
Iron is coated with zinc to prevent rusting. The process is called
annealing
tempering
calcining
galvanising
The noble gas which is present in microscopic quantities in air is
xenon
krypton
argon
helium
The pH or pure water is nearly 7.0 It will increase on the addition or
hydrochloric acid
ammonia
cane sugar
common salt
Which among the following is a local anaesthetic?
Chloroform
Morphine
Streptomycin
Cocaine
Laughing gas is
nitric oxide
nitrogen peroxide
nitrogen pentoxide
nitrous oxide
Artificial diamonds were produced by
Moissan
Davy
Faraday
Marie Curie
Jeweller's rouge is
magnetic oxide of iron
ferric oxide
ferrous oxide
ferrous carbonate
Fructose is also called
dextrose
fruit sugar
beet sugar
blood sugar
Brass contains
copper and tin
aluminium and magnesium
copper and zinc
copper, tin and zinc
In the common soda-acid fire extinguisher, the fire is put out by
acid fumes
sodium bicarbonate
carbon dioxide
sodium carbonate
Even as early as 3000 BC glass was known to the
Europeans
Egyptians
Asians
Americans
Oil of winter green contains
acetone
ether
acetic acid
methyl salicylate
Dust particles in the air of large industrial cities are removed by
Sedimentation
Electrophoresis
Tyndall effect
Brownian movement
Which of the following is a Bleaching agent?
Potassium chlorate
Hydrogen peroxide
Copper sulphate
Silver Nitrate
The main element used in the vulcani-sation of rubber is
nickel
copper
sulphur
graphite
Which of the following is not a chemical change?
Rusting of iron
Burning of magnesium
Sublimation of iodine
Electrolysis of water
What is 'oxygen mixture'?
A mixture of potassium nitrate and carbon
A mixture of ammonium chloride and sodium nitrate
A mixture of potassium chlorate and manganese dioxide
A mixture of ammonium nitrate and charcoal
The depletion of the ozone layer in the upper atmosphere is due to -extensive use of
dichloro-phenoxy-acetic acid
superphosphate of lime
chlorofluorocarbons (CFC)
dichloro-diphenyl-trichloro-ethane
Glass articles are annealed so that
they may appear better
they can resist the action of acids and alkalies
they lose their brittleness
they can withstand temperature shocks
Optical instruments are made of
pyrex glass
flint glass
quartz glass
Crooke's glass
Penicillin was discovered by
Alexander Fleming
Sir JJ Thomson
Dr Nessler
Sir John Russel
The science which deals with the chemistry of life processes is known as
electrochemistry
physical chemistry
biochemistry
tinctorial chemistry
The Long Form of the Periodic Table is based on
atomic number
valency
atomic mass
atomic radius
The ore of iron is
Dolomite
Magnetite
Bauxite
Anglesite
Which of the following represents a physical change?
sublimation
oxidation
reduction
decomposition
Concrete is a mixture of
cement an limestone
cement and sand
cement and gravel
cement, sand and gravel
The name rubber was given by
Lavoisier
Priestley
Dalton
Avogadro
The fertilizer which has the largest percentage of nitrogen is
urea
ammonium nitrate
ammonium sulphate
calcium cyanamide