*Сhemistry.Oxygen*3*22*1*

#599

*!Oxygen had been produced by several chemists prior to its discovery in 1774, but they failed to recognize it as a distinct element. Joseph Priestley and Carl Wilhelm Scheele both independently discovered oxygen, but Priestly is usually given credit for the discovery. They were both able to produce oxygen by heating mercuricoxide

(Hg O).

 Which title is the most suitable one to this passage?

*Discovery of Nitrogen

*Discovery of Hydrogen

*Discovery of Helium

*+Discovery of Oxygen

*Discovery of Mercury

#600

*!Priestley called the gas produced in his experiments “dephlogisticated air“ and Scheele called it 'fire air'. The name oxygen was created by Antoine Lavoisier who incorrectly believed that oxygen was necessary to form all acids.

Which title is the most suitable one to this passage?

*The term “Mercury”

*The term “Helium”

*The term “Nitrogen”

*+The term “Oxygen”

*The term “Hydrogen”

#601

*!Oxygen is the third most abundant element in the universe and makes up nearly 21% of the earth's atmosphere. Oxygen accounts for nearly half of the mass of the earth's crust, two thirds of the mass of the human body and nine tenths of the mass of water. 

Which title is the most suitable one to this passage?

*Main characteristics ofSodium

*Main characteristics of Nitrogen

*Main characteristics of Helium

*+Main characteristics ofOxygen

*Main characteristics ofHydrogen

#602

*!Large amounts of oxygen can be extracted from liquefied air through a process known as fractional distillation. Oxygen can also be produced through the electrolysis of water or by heating potassium chlorate (KClO₃).

Which title is the most suitable one to this passage?

*Production of Sodium

*Production of Helium

*Production of Hydrogen

*Production of Nitrogen

*+Production of Oxygen

#603

*!Oxygen is a highly reactive element and is capable of combining with most other elements. It is required by most living organisms and for most forms of combustion. Impurities in molten pig iron are burned away with streams of high pressure oxygen to produce steel. Oxygen can also be combined with acetylene (C₂H₂) to produce an extremely hot flame used for welding. 

Which title is the most suitable one to this passage?

*Properties of Carbon

*Properties of Nitrogen

*+Properties of Oxygen

*Properties of Hydrogen

*Properties of Helium

#604

*!Liquid oxygen, when combined with liquid hydrogen, makes an excellent rocket fuel. Ozone (O₃) forms a thin, protective layer around the earth that shields the surface from the sun's ultraviolet radiation. Oxygen is also a component of hundreds of thousands of organic compounds.

Which title is the most suitable one to this passage?

*Compounds of Iron

*+Compounds of Oxygen

*Compounds of Nitrogen

*Compounds of Hydrogen

*Compounds of Mercury

#605

*!Chemistry is the study of matter, and all matter is made up of atoms. We will learn about elements, atomic number and mass, isotopes, chemistry moles and compounds.

Which title is the most suitable one to this passage?

*+Chemistry as a science

*Biology as a science

*Pharmacy as a science

*Pharmacology as a science

*Botany as a science

#606

*!A little more than a century ago, the chemist Dmitri Mendeleyev published an early form of the periodic table, which organizes the known elements of our world. His method of classifying the elements was so useful that we still use it even today. We will learn to apply this elegant table to an understanding of atomic structure and properties, including periodic table trends.

Which title is the most suitable one to this passage?

*D. I. Mendeleyev’s biography

*D. I.Mendeleyev’s periodic law

*The Periodic law

*+The Periodic table

*D. I.Mendeleyev’s scientific activity

#607

*!Properties of gases can be modeled using some relatively simple kineticequations, which we can relate to the behavior of individual gas molecules. We will learn about the ideal gas law, vapor pressure, partial pressure, and the Maxwell Boltzmann distribution.

Which title is the most suitable one to this passage?

*Liquids and the kinetic molecular theory

*Solids and the kinetic molecular theory

*+Gases and the kinetic molecular theory

*Metals and the kinetic molecular theory

*Acids and the kinetic molecular theory

#608

*!Many chemical reactionsare reversible, and the forward and backward reactions can occur at the same time. When therate of the forward reaction is equal to the rate of the backward reaction, we call that a dynamic equilibrium. We will learn how equilibrium can be described by the equilibrium constant K, and how different factorsthan can affect the chemical equilibrium.

Which title is the most suitable one to this passage?

*Physical equilibrium

*Biological equilibrium

*Natural equilibrium

*+Chemical equilibrium

*Experimental equilibrium

#609

*!Nuclear chemistry and radioactivity can treat cancer and make your watch glow in the dark. We will learn about radioactive decay, nuclear stability, carbon dating, half-life, and what is happening on a subatomic level during a nuclear reaction.

Which title is the most suitable one to this passage?

*Biochemistry

*Physical Chemistry

*Organic Chemistry

*Inorganic Chemistry

*+Nuclear Chemistry

#610

*!Oxidation and reduction reactions power your phone and make it possible for your body to use the oxygen you inhale. We will learn about oxidation states (numbers), oxidation-reduction (redox) reactions, galvanic/voltaic cells, electrolytic cells, cell potentials, and how electrochemistry is related to thermodynamics and equilibrium.

Which title is the most suitable one to this passage?

*Redox reactions and Biochemistry

*Redox reactions and Nuclear Chemistry

*Redox reactions and Physical Chemistry

*Redox reactions and Inorganic Chemistry

*+Redox reactions and Electrochemistry

#611

*!In this section we will be talking about the basics of acids and bases and how acid-base chemistry is related to equilibria. We will cover acid and base definitions, pH, acid-base equilibria, acid-base properties of salts, and the pH of salt solutions.

Which title is the most suitable one to this passage?

*Salts and Alkalis

*Acids and Salts

*+Acids and Bases

*Solids and Liquids

*Liquids and Gases

#612

*!The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. This biogeochemical cycledescribes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration and decay remove it from the atmosphere.

Which title is the most suitable one to this passage?

*TheHydrogen cycle

*TheNitrogen  cycle

*TheHelium cycle

*+TheOxygen cycle

*TheCarbon cycle

#613

*!Free oxygen also occurs in solution in the world's water bodies. The increased solubility of O₂ at lower temperatures has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content. Water polluted with plant nutrients such as nitrates or phosphates may stimulate growth of algae by a process called eutrophication and the decay of these organisms and other biomaterials may reduce amounts of O₂ in eutrophic water bodies.

Which title is the most suitable one to this passage?

*Free Carbon

*Free Hydrogen

*+Free Oxygen

*FreeNitrogen 

*Free Silica

#614

*!The free oxygen partial pressure in the body of a living vertebrate organism is highest in the respiratory system, and decreases along any arterial system, peripheral tissues and venous system, respectively. Partial pressure is the pressure which oxygen would have if it alone occupied the volume.

Which title is the most suitable one to this passage?

*The free Nitrogen partial pressure

*+The free Oxygen partial pressure

*The free Hydrogen partial pressure

*The free Helium partial pressure

*The free Argon partial pressure

#615

*!What Lavoisier did (although this was disputed at the time) was to conduct the first adequate quantitative experiments on oxidation and give the first correct explanation of how combustion works. He used these and similar experiments, all started in 1774, to discredit the phlogiston theory and to prove that the substance discovered by Priestley and Scheele was a chemical element.

Which title is the most suitable one to this passage?

*Lavoisier contribution in the discovery ofNitrogen

*Lavoisier contribution in the discovery ofHydrogen

*+Lavoisier contribution in the discovery ofOxygen

*Lavoisier contribution in the discovery ofHelium

*Lavoisier contribution in the discovery ofArgon

#616

*!Oxygen storage methods include high pressure oxygen tanks, cryogenics and chemical compounds. For reasons of economy, oxygen is often transported in bulk as a liquid in specially insulated tankers.

Such tankers are used to refill bulk liquid oxygen storage containers, which stand outside hospitals and other institutions with a need for large volumes of pure oxygen gas. Oxygen is also stored and shipped in smaller cylinders containing the compressed gas; a form that is useful in certain portable medical applications.

Which title is the most suitable one to this passage?

*The storage ofMercury

*The storage of Carbon

*The storage ofHydrogen

*+The storage ofOxygen

*The storage ofWater

#617

*!Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry deals with such topics as the properties of individual atoms, how atoms form chemical bonds to create chemical compounds, the interactions of substances through intermolecular forces that give matter its general properties, and the interactions between substances through chemical reactions to form different substances.

Which title is the most suitable one to this passage?

*Biochemistry

*Biology

*Botany

*+Chemistry

*Pharmacology

#618

*!Scholars disagree about the etymology of the word chemistry. The history of chemistrycan be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from the word alchemy, an earlier set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism and medicine; it is commonly thought of as the quest to turn lead or another common starting material into gold.

Which title is the most suitable one to this passage?

*The etymology of the word “Biology”

*The etymology of the word “Biochemistry”

*The etymology of the word “Botany”

*The etymology of the word “Physics”

*+The etymology of the word “Chemistry”

#619

*!The year 2011 was declared by the United Nations as the International Year of Chemistry. It was an initiative of the International Union of Pure and Applied Chemistry and of the United Nations Educational, Scientific, and Cultural Organization and involves chemical societies, academics, and institutions worldwide and relied on individual initiatives to organize local and regional activities.

Which title is the most suitable one to this passage?

*The International Year of Physics

*The International Year of Biology

*The International Year of Pharmacology

*+The International Year of Chemistry

*The International Year of Botany

#620

*!A chemical reaction is a transformation of some substances into one or more different substances. The basis of such a chemical transformation is the rearrangement of electrons in the chemical bonds between atoms. It can be symbolically depicted through a chemical equation, which usually involves atoms as subjects. The number of atoms on the left and the right in the equation for a chemical transformation is equal.The type of chemical reactions a substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws.

Which title is the most suitable one to this passage?

*A physical reaction 

*A biochemical reaction 

*A pharmacological reaction 

*A biological reaction 

*+A chemical reaction