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the physical universe

Questions and Answers of The Physical Universe

The number of moles of carbon present in 3 mol of glucose, C6H12O6, isa. 2b. 3c. 6d. 18
How many moles of H atoms are present in 1 mol of H2O?a. 2/3b. 1c. 2d. 3
Which of the following are exothermic reactions and which are endothermic?a. The explosion of dynamiteb. The burning of methanec. The decomposition of water into its elementsd. The dissociation of
An oxygen atom has a mass of 16.0 u. The number of moles of molecular oxygen, O2, in 64 g of oxygen gas isa. 2b. 4c. 32d. 64
The formula mass of gaseous carbon dioxide, CO2,a. is 28 ub. is 44 uc. is 56 ud. depends on the mass of the sample
In what fundamental way is the explosion of an atomic bomb different from the explosion of dynamite?
A mole of any compound contains Avogadro’s number ofa. atomsb. ionsc. moleculesd. formula units
One mole of an element has a mass equal toa. Avogadro’s numberb. its atomic number expressed in gramsc. its mass number expressed in gramsd. its atomic mass expressed in grams
How much sulfur is needed to react with 200 g of potassium to form potassium sulfide, K2S?
A fuel cell does not requirea. a positive electrodeb. a negative electrodec. oxidation-reduction reactionsd. recharging
Batteries and fuel cells employa. oxidation reactions onlyb. reduction reactions onlyc. both oxidation and reduction reactionsd. acid-base neutralization reactions
How much chlorine is needed to react with 50 g of sodium to form sodium chloride, NaCl? How much sodium chloride is produced?
The quantity actually stored in a storage battery isa. electric chargeb. electric currentc. voltaged. energy
When an electric current is passed through molten sodium chloride,a. sodium metal is deposited at the positive electrodeb. sodium ions are deposited at the positive electrodec. chlorine gas is
Three compounds used as fertilizers are urea, CO(NH2)2; ammonium nitrate, NH4NO3; and ammonium sulfate, (NH4)2SO4. What is the percentage of nitrogen by mass in each compound? (Divide the formula
A catalyst affects which one or more of the following?a. the energy needed for a chemical reaction to occurb. the energy a chemical reaction gives offc. the speed of a chemical reactiond. whether a
When a substance gains electrons in a chemical reaction, the substance is said to bea. reducedb. oxidizedc. electrolysedd. activated
How many moles of glucose are present in 500 kg of glucose, C6H12O6?
When a gas reaction involves a decrease in the total number of molecules, the equilibrium can be shifted in the direction of higher yield bya. increasing the pressureb. decreasing the pressurec.
The yield of the product C in the reversible reaction A + B + energy ⇌ C can be increased bya. decreasing the temperatureb. increasing the temperaturec. increasing the surface area of the
Find the mass of 2 mol of iron(III) oxide, Fe2O3.
At equilibrium,a. both forward and reverse reactions have ceasedb. the forward and reverse reactions are proceeding at the same ratec. the forward reaction has come to a stop, and the reverse
When the temperature at which a certain reversible reaction occurs is increased, the final amount of the reaction product(s)a. increasesb. remains the samec. decreasesd. does any of the above,
Find the mass of 10 mol of uranium, U. How many atoms are present in such a sample?
The speeds of reactions between ions in solutiona. depend critically upon temperatureb. are essentially independent of temperaturec. depend upon which catalyst is usedd. are slow in general
For a reaction that occurs near room temperature, an increase of 10°Ca. has little effect on the reaction speedb. increases the reaction speed by about 10 percentc. increases the reaction speed by
Ammonia is produced by the reaction N2 + 3H2 → 2NH3. How many moles of N2 and how many of H2 are needed to produce 1 mol of ammonia?
Reaction rates increase with temperature primarily becausea. dissociation into ions is more completeb. more collisions occur between the molecules involvedc. more activated molecules are formedd.
The neutralization of a strong acid by a strong basea. absorbs energyb. liberates energyc. involves no energy changed. requires a catalyst to occur
How many moles of propane, C3H8, can be prepared from 1 mol of carbon? From 1 mol of hydrogen?
When a catalyst promotes a chemical reaction, it usually does so bya. providing energyb. providing electronsc. producing activated moleculesd. becoming permanently altered
The energy change in a chemical reaction depends ona. the bond energies of the reactantsb. the bond energies of the productsc. both of the aboved. neither of the above
How many moles of aluminum are present in 5 mol of MgAl2O4?
If a given reaction is exothermic, the reverse reactiona. is exothermicb. is endothermicc. may involve no energy changed. any of these, depending on the reaction
An example of an endothermic reaction isa. the dissociation of a salt in waterb. the neutralization of an acid by a basec. the freezing of waterd. combustion
Which of the following quantities are the same for both a mole of hydrogen molecules and a mole of oxygen molecules at the same temperature:(a) The mass of each sample; (b) The number of
A chemical reaction that absorbs energy is calleda. endothermicb. exothermicc. activatedd. oxidation-reduction
When 1 g of a metal is oxidized, the resulting oxide has a mass that isa. less than 1 gb. equal to 1 gc. more than 1 gd. any of these, depending on the metal
What role does air play in combustion?
A substance of unknown composition is heated in an open container. As a result,a. its mass decreasesb. its mass remains the samec. its mass increasesd. any of these can occur, depending on the nature
The chief constituent of dry air isa. oxygenb. nitrogenc. carbon dioxided. argon
What aspect of Lavoisier’s work marked the beginning of chemistry as a science?
When something burns,a. it combines with phlogistonb. it gives off phlogistonc. it combines with oxygend. it gives off oxygen
How could you prepare the weak acid H2S from the salt Na2S (sodium sulfide)?
The Al3+ ion tends to form AlOH2+ ions in water solution. Would you expect a solution of AlCl3 to be acidic, basic, or neutral? Why?
The fertilizer ammonium sulfate can be made by using sulfuric acid to neutralize a solution of ammonia in water. Give the overall equation of the process.
What salt is formed when a solution of potassium hydroxide is neutralized by acetic acid, HC2H3O2? Give the equation of the process.
What salt is formed when a solution of calcium hydroxide is neutralized by hydrochloric acid? Give the equation of the process.
Give the ionic equation for the neutralization of potassium hydroxide by nitric acid. What chemical changes does this equation show?
A concentrated solution of which of the following has the highest pH?a. hydrochloric acidb. acetic acidc. sodium hydroxided. ammonia
Justify the statement that water is both a weak acid and a weak base.
A concentrated solution of which of the following has the lowest pH?a. hydrochloric acidb. acetic acidc. sodium hydroxided. ammonia
A pH of 7 signifies a (an)a. acid solutionb. basic solutionc. neutral solutiond. solution of polar molecules
Which is more strongly acidic, a solution of pH 3 or one of pH 5? Which is more strongly basic, a solution of pH 8 or one of pH 10?
Pure water containsa. only H+ ionsb. only OH- ionsc. both H+ and OH- ionsd. neither H+ nor OH- ions
A strong acid or base in solution is completelya. dissociatedb. neutralizedc. hydrolyzedd. precipitated
What is the difference, if any, between a basic solution and an alkaline solution?
The formula for iron(III) hydroxide isa. FeOHb. Fe3OHc. Fe(OH)3d. Fe3(OH)3
The net reaction between a strong acid and a strong base isa. H2O → H+ + OHb. H+ + OH- → H2Oc. H2O + H2O → H3O+ + OHd. H+ + H2O → H3O+
Would you expect HBr to be a weak or strong acid? Why?
The symbol of the ammonium ion isa. NH3 -b. NH 3 +c. NH 4 -d. NH 4 +
A substance whose formula does not contain OH yet yields a basic solution when dissolved in water isa. NH3b. CO2c. HCld. NaCl
Do pure acids in the liquid state contain H+ ions? If not, what do such acids consist of?
A base dissolved in water liberatesa. H-.b.OHc. OH+d. OH-
A common strong acid isa. acetic acidb. boric acidc. nitric acidd. citric acid
(a) Is the percentage of the world’s water that is freshwater 1 percent? 3 percent? 10 percent? 50 percent? (b) Is the proportion of freshwater in the form of ice in the polar regions about
While it is convenient to regard acidic solutions as containing H+ ions, it is more realistic to describe them as containinga. hydronium ionsb. hydroxide ionsc. polar moleculesd. hydrogen atoms
The reason pure acids in the liquid state are not dissociated is that their chemical bonds area. ionicb. covalentc. metallicd. van der Waals
When water that contains Ca2+ and HCO3- ions is heated, calcium carbonate precipitates out. Carbon dioxide and something else are also produced. What is the something else? Give the equation of the
Acids invariably containa. hydrogenb. oxygenc. chlorined. water
The ions usually responsible for “hard” water area. H+ and OH-.b. Na+ and Cl-.c. Ca2+ and Mg2+d. SO 42 - and NO 3 -
How does the reactivity of the chloride ion Cl- compare with the reactivity of the chlorine molecule Cl2? Does the answer depend on temperature?
The average salinity of seawater is abouta. 0.1 percentb. 1.5 percentc. 3.5 percentd. 10 percent
When an electrolyte is dissolved in water,a. the freezing point of the water is raisedb. the solution is acidicc. the solution contains free ionsd. the solution contains free electrons
You have a solution that contains Ag+ ions and another that contains Na+ ions. How would adding a solution that contains Cl- ions to these solutions enable you to tell which is which?
Dissociation refers toa. the formation of a precipitateb. the separation of a mixture of polar and nonpolar liquids (such as oil and water) into separate layersc. the separation of a solution
The ions and atoms (or molecules) of an elementa. have very nearly the same properties except that the ions are electrically chargedb. may have strikingly different propertiesc. always exhibit
You have a solution that contains Cl- ions and another that contains NO 3- ions. How would adding a solution that contains Ag+ ions to these solutions enable you to tell which is which?
Which of the following has the least ability to conduct electric current?a. an acid solutionb. a basic solutionc. a salt solutiond. a nonpolar liquid
Which of the following would you expect to be a strong electrolyte in solution?a. H2Ob. HClc. sugard. alcohol
How could you distinguish experimentally between an electrolyte and a nonelectrolyte?
A substance that separates into free ions when dissolved in water is said to bea. polarb. saturatedc. an electrolyted. covalent
Nonpolar substances usually dissolve most readily ina. polar liquidsb. nonpolar liquidsc. acidsd. bases
You have saturated solutions of sodium nitrate (NaNO3) and potassium nitrate (KNO3) at 60°C. What is an easy way to tell which is which?
In general, ionic compoundsa. are insoluble in all liquidsb. dissolve best in polar liquidsc. dissolve best in nonpolar liquidsd. dissolve equally well in polar and nonpolar liquids
The most strongly polar liquid of the following isa. waterb. alcoholc. a detergentd. gasoline
Give two ways to tell whether a sugar solution is saturated or not.
A molecule that behaves as though positively charged at one end and negatively charged at the other is called a (an)a. hydronium ionb. acid moleculec. polar moleculed. nonpolar molecule
Dissolving a solute in a liquida. decreases the liquid’s freezing pointb. increases the liquid’s freezing pointc. does not change the liquid’s freezing pointd. does any of these, depending on
How do unsaturated, saturated, and supersaturated solutions differ?
A solid is dissolved in a liquid. When the temperature of the solution is increased, the solubility of the solida. increasesb. decreasesc. remains the samed. does any of these, depending upon the
A gas is dissolved in a liquid. When the temperature of the solution is increased, the solubility of the gasa. increasesb. decreasesc. remains the samed. any of these, depending upon the nature of
Why do bubbles of gas form in a glass of soda water when it warms up?
A saturated solution is a solution thata. contains the maximum amount of soluteb. contains the maximum amount of solventc. is in the process of crystallizingd. contains polar molecules
Suppose there were molecules that had no attraction whatever for one another. A collection of such molecules would form a (an)a. gasb. liquidc. amorphous solidd. crystalline solid
What ions would you expect to find in the crystal structures of CaF2 and KI?
Diamond and graphite are forms of solid carbon. They botha. conduct electricity wellb. can be used as lubricantsc. are very hardd. form CO2 when burned in air
A property of metals that is not due to the electron sea in them is their ability toa. conduct electricityb. conduct heatc. reflect lightd. form oxides
Van der Waals forces are strong enough to hold inert gas atoms together to form liquids at low temperatures, but these forces do not lead to inert gas molecules at higher temperatures. Why not?
Diamond is an example ofa. a covalent solidb. an ionic solidc. a metallic solidd. a molecular solid

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