*Nitrogen. Water*3*22*1*
#730
*!Nitrogen
occur in the free state in air, of which it forms four-fifth by
volume. Nitrogen exists in the state of combination in nitre or
salpetre, potassium nitrate,
.
It forms an essential constituent of the bodies of all animals and
plants.
Which title is the most suitable one to this passage?
*Nitrogen properties
*+Nitrogen occurrence
*preparation of Nitrogen
*potassium nitrate
*essential constituent
#731
*!Nitrogen is a colourless, transparent, tasteless and inodorous gas. It neither supports combustion, nor burns, Nitrogen is slightly soluble in water, 1000 parts of water are able to dissolve 28 parts of the gas. By great cold and great pressure nitrogen is reduced to the liquid and even to the solid state.
Which title is the most suitable one to this passage?
*+properties of Nitrogen
*preparation of Nitrogen
*occurrence of Nitrogen
*inodorous gas
*tasteless gas
#732
*!Nitrogen
can be prepared by burning phosphorus in closed volume of air. Oxygen
is entirely removed. After whit fumes of phosphorus pentoxide (
)
have disappeared, the colourless gas remaining is nearly pure
nitrogen.
Which title is the most suitable one to this passage?
*properties of Nitrogen
*+preparation of Nitrogen
*burning phosphorus
*phosphorus pentoxide
*colourless gas
#733
*!Water is a compound substance which consists of two elements – hydrogen and oxygen. Water is widely distributed in nature in its states of aggregation – steam or aqueous vapor, liquid water and solid ice or snow.
Which title is the most suitable one to this passage?
*+water structure
*aqueous vapor
*solid ice
*water pollution
*compound substance
#734
*!Water boils 100º under 760 mm pressure. Steam or water vapour is an invisible colourless gas that condenses to a visible cloud of small particles when it comes in contact with the atmosphere. Liquid water freezes at 0ºC into crystalline ice. Water plays a vital part in the nutrition of animals and plants.
Which title is the most suitable one to this passage?
*+water properties
*small particles
*water pollution
*odourless liquid
*nutrition of animals
#735
*!Water may be purified by boiling. The boiling will kill any germs, which may be present in water. Water is purified by distillation. The liquid which distils or passes over is called the distillate. In chemical laboratories ordinary water is distilled in order to purify it for fine work with chemical substances.
Which title is the most suitable one to this passage?
*+distillation of water
*chemical substances
*chemical laboratories
*water pollution
*water properties
#736
*!Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalentlybonded to a single oxygen atom. Water appears in nature in all three common states of matter (solid, liquid, and gas) and may take many different forms on Earth.
Which title is the most suitable one to this passage?
*+chemical properties of water
*chemical laboratories
*odour and taste of water
*different forms on Earth
*three common states
#737
*!Pure H2O is tasteless and odorless. Water can dissolve many different substances, giving it varying tastes and odors. The taste of spring water and mineral water, often advertised in marketing of consumer products, derives from the minerals dissolved in it.
Which title is the most suitable one to this passage?
*+odour and taste of water
*different substances
*natural minerals
*water structure
*marketing of consumer products
#738
*!Sea water contains about 3.5% salt on average, plus smaller amounts of other substances. The physical properties of sea water differ from fresh water in some important respects. It freezes at a lower temperature (about −1.9 °C). The salinity of water in major seas varies from about 0.7% in the Baltic Sea to 4.0% in the Red Sea.
Which title is the most suitable one to this passage?
*+Sea water
*Baltic Sea
*Red Sea
*water pollution
*freezing water
#739
*!The human body contains from 55% to 78% water, depending on body size. To function properly, the body requires between one and seven liters of water per day to avoid dehydration. People can drink far more water than necessary while exercising, however, putting them at risk of water intoxication (hyper hydration), which can be fatal.
Which title is the most suitable one to this passage?
*+water consumption
*water pollution
*water structure
*preparation of water
*mineral water
#740
*!Nitrogen is important to the chemical industry. It is used to make fertilisers, nitric acid, nylon, dyes and explosives. To make these products, nitrogen must first be reacted with hydrogen to produce ammonia. This is done by the Haber process. 150 million tonnes of ammonia are produced in this way every year.
Which title is the most suitable one to this passage?
*+the use of Nitrogen
*chemical industry
*making explosives
*nitric acid
*producing ammonia
#741
*!Nitrogen is formally considered to have been discovered by Scottish physician Daniel Rutherford in 1772, who called it noxious air. Though he did not recognize it as an entirely different chemical substance, he clearly distinguished it from Joseph Black's "fixed air", or carbon dioxide.
Which title is the most suitable one to this passage?
*+history of Nitrogen
*preparation of Nitrogen
*carbon dioxide
*chemical substance
*Daniel Rutherford
#742
*!Nitrogen gas is also used to provide an unreactive atmosphere. It is used in this way to preserve foods and in the electronics industry during the production of transistors and diodes. Large quantities of nitrogen are used in annealing stainless steel and other steel mill products.
Which title is the most suitable one to this passage?
*+the use of nitrogen gas
*unreactive atmosphere
*large quantities of nitrogen
*stainless steel
*steel mill products
#743
*!Liquid nitrogen is a cryogenic liquid. Liquid nitrogen is often used as a refrigerant. It is used for storing sperm, eggs and other cells for medical research and reproductive technology. It is also used to rapidly freeze foods, helping them to maintain moisture, colour, flavour and texture.
Which title is the most suitable one to this passage?
*+the use of liquid nitrogen
*reproductive technology
*quantities of nitrogen
*nitrogen occurrence
*cryogenic liquid
#744
*!Liquid nitrogen is often used as a refrigerant. It is used for storing sperm, eggs and other cells for medical research and reproductive technology. It is also used to rapidly freeze foods, helping them to maintain moisture, colour, flavour and texture.
What is liquid nitrogen used for?
*+for storing sperm and eggs
*providing an unreactive atmosphere
*avoiding dehydration
*producing transistors and diodes
*burning phosphorus
#745
*!The human body contains from 55% to 78% water, depending on body size. To function properly, the body requires between one and seven liters of water per day to avoid dehydration. People can drink far more water than necessary while exercising, however, putting them at risk of water intoxication (hyper hydration), which can be fatal.
Why do we drink water?
*+to avoid dehydration
*to avoid hyper hydration
*to recognize chemical substance
*to lose weight
*to put on weight
#746
*!Water is a compound substance which consists of two elements – hydrogen and oxygen. Water is widely distributed in nature in its states of aggregation – steam or aqueous vapor, liquid water and solid ice or snow.
What does water consist of?
*hydrogen and nitrogen
*+hydrogen and oxygen
*nitrogen and oxygen
*methane and hydrogen
*uranium and oxygen
#747
*!Nitrogen can be prepared by burning phosphorus in closed volume of air. Oxygen is entirely removed. After whit fumes of phosphorus pentoxide ( ) have disappeared, the colourless gas remaining is nearly pure nitrogen.
How is nitrogen prepared by?
*steeping phosphorus
*freezing phosphorus
*+burning phosphorus
*removing oxygen
*dissolving oxygen
#748
*!Liquid nitrogen is a cryogenic liquid. Liquid nitrogen is often used as a refrigerant. It is used for storing sperm, eggs and other cells for medical research and reproductive technology. It is also used to rapidly freeze foods, helping them to maintain moisture, colour, flavour and texture.
What is liquid nitrogen?
*unctuous
*alcoholic
*+cryogenic
*homogenous
*ascorbic
#749
*!Liquid water has importance as a solvent, a solute, a reactant and a biomolecule, structuring proteins, nucleic acids and cells and controlling our consciousness. Life cannot evolve or continue without liquid water, which is why there is so much excitement about finding it on Mars and other planets and moons. It is unsurprising that water plays a central role in many of the World's religions.
Which title is the most suitable one to this passage?
*water pollution
*+the importance of water
*nucleic acids
*World’s religions
*distillation of water
#750
*!Water pollution is the contamination of water bodies. Water pollution affects the entire biosphere – plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and population, but also to the natural biological communities.
Which title is the most suitable one to this passage?
*water bodies
*biological communities
*individual species
*+water pollution
*entire biosphere
#751
*!Water plays a vital part in the nutrition of animals and plants. Water may be purified by boiling. The boiling will kill any germs, which may be present in water. Water is purified by distillation. The liquid which distils or passes over is called the distillate. In chemical laboratories ordinary water is distilled in order to purify it for fine work with chemical substances.
How is water purified?
*by melting
*+by boiling
*by burning
*by heating
*by soaking