Final Chemistry Midterm

In the stepwise preparation of pure calcium carbonate from limestone, the step referred to as calcination involves: A) thermal decomposition of calcium carbonate to calcium oxide B) the addition of water to calcium oxide to form calcium hydroxide C) bubbling carbon dioxide through aqueous calcium hydroxide D) heating calcium oxide with carbon to form calcium metal E) melting of calcium oxide

A) thermal decomposition of calcium carbonate to calcium oxide

The Solvay process involves a reaction of sodium chloride, ammonia, and carbon dioxide in aqueous solution. Of the various possible products, the one least soluble in water is: A) ammonium bicarbonate B) "baking soda" (NaHCO₃) C) "sal ammoniac" (NH₄Cl) D) "table salt" (NaCl" E) "washing soda" (Na₂CO₃)

B) "baking soda" (NaHCO₃)

What mass of potassium superoxide could be prepared from 15.6 g of potassium metal and excess oxygen? A) 37.6 g B) 15.6 g C) 22.0 g D) 28.4 g E) 0.399 g

B) 15.6 g

Write the general reaction for a group 1 (1A) metal with water: A) 2M(s) + 2H₂O(l) →H₂O₂(aq) + 2MH(s) B) 2M(s) +2H₂O(l) →2MOH(aq) + H₂(g) C) M(s) + H₂O(l) →MO(s) + H₂(g) D) 2M(s) + H₂O(l) → M₂O(s) + H₂(g) E) 2M(s) + 2H₂O(l) → M(OH)₂(s) + H₂(g)

B) 2M(s) +2H₂O(l) →2MOH(aq) + H₂(g)

Write the equation for the electrolysis of molten NaCl. A) 2NaCl(s) → 2Na(s) + Cl₂(g) B) 2NaCl(l) → 2Na(l) + Cl₂(g) C) 2NaCl(l) → Na₂Cl₂(s) D) 2NaCl(l) → Na(s) + NaCl₂(s) E) There is no reaction.

B) 2NaCl(l) → 2Na(l) + Cl₂(g)

Which element forms the largest variety of oxoanions? A) S B) Cl C) P D) Br E) I

B) Cl

Which of the following has the lowest boiling point? A) Bromine B) Fluorine C) Iodine D) Chlorine E) Astatine

B) Fluorine

Which of the following statements describes an uncommon use of an element? A) Aluminum is used in light-weight alloys. B) Gallium is used in the thermite reaction. C) Gallium is used in the electronics industry. D) Indium is used to make low-melting alloys. E) A possible use for thallium is in high-temperature superconductors.

B) Gallium is used in the thermite reaction.

Choose the INCORRECT statement. A) HI is a strong acid B) HF is a strong acid C) HCl is a strong acid D) HBr is a strong acid E) HF will etch glass

B) HF is a strong acid

Choose the INCORRECT statement. A) Elemental silicon is produced by reduction of SiO₂ with coke. B) In silica each silicon atom is bonded directly to four other silicon atoms. C) Coke is made by heating coal in the absence of air. D) Charcoal is made by heating wood in the absence of air. E) Allotropes of carbon include diamond, graphite, fullerenes and nanotubes.

B) In silica each silicon atom is bonded directly to four other silicon atoms.

Choose the INCORRECT statement. A) The Frasch process is a method of mining sulfur. B) Photoconductivity is the production of photons by the use of electricity. C) Selenium displays the property of photoconductivity. D) Polonium is a rare radioactive metal. E) Sulfur is used in vulcanizing rubber, as a pesticide and to produce sulfuric acid.

B) Photoconductivity is the production of photons by the use of electricity.

Choose the INCORRECT statement about silicon. A) Silicon forms on stable oxide. B) Silicon exhibits more catenation than carbon. C) Sand and quartz are SiO₂. D) The central feature of silicates is the SiO₄⁴⁻ tetrahedron. E) A silicone is a compound with an alternating silicon and oxygen chain as a backbone with carbon containing groups as sidechains.

B) Silicon exhibits more catenation than carbon.

Choose the INCORRECT statement. A) Xenon compounds in several different oxidation states have been formed. B) The noble gas compounds are very stable. C) Xenon compounds are excellent reducing agents. D) The Noble gas (except helium) electron configuration has ns²np⁶. E) Although predicted in the 1930s, it was 1962 before noble gas compounds were made.

B) The noble gas compounds are very stable.

Choose the incorrect statement about the alkaline earth metals A) The heavier Group 2 (2A) metals are nearly as active as the Group 1 (1A) metals B) They are the Group 1 (1A) family C) Magnesium metal is produced by the Dow process D) Salts of Sr and Ba provide vivid colors for pyrotechnic displays E) The source of magnesium is seawater and natural brines

B) They are the Group 1 (1A) family

Choose the INCORRECT oxidation state for xenon in the listed molecule. A) XeF₂/+2 B) XeO₃/+4 C) XeF₆/+6 D) XeO₄/+8 E) XeOF₂/+4

B) XeO₃/+4

Which of the following forms a complete set of oxyacids in which it exhibits the oxidation states of +1, +3, +5, and +7? A) fluorine B) chlorine C) bromine D) iodine E) astatine

B) chlorine

Which of the following name/formula combinations is INCORRECT? A) dioxygen/O₂ B) familiar oxygen/O C) trioxygen/O₃ D) ozone/O₃ E) potassium superoxide/KO₂

B) familiar oxygen/O

Lithium differs from other members of the group 1 (1A) elements in which way? A) It does not react with water under any conditions B) It forms a nitride C) Its hydroxide is very soluble D) it is a rather soft metal E) it is a good reducing agent

B) it forms a nitride

Bromine can be produced by: A) oxidizing Cl₂ with Br⁻ B) oxidizing Br⁻ with Cl₂ C) oxidizing Br⁻ with I₂ D) oxidizing I⁻ with Br⁻ E) oxidizing F⁻ with Br⁻

B) oxidizing Br⁻ with Cl₂

Finish the following reaction: Li(s) + O₂(g) → A) 2Li(s) + O₂(g) → Li₂O₂(s) B) 2Li(s) + O₂(g) → 2LiO(s) C) 4Li(s) + O₂(g) → 2Li₂O(s) D) Li(s) + O₂(g) → LiO₂(s) E) There is no reaction

C) 4Li(s) + O₂(g) → 2Li₂O(s)

An aqueous solution of boric acid can be represented by the equilibrium system: B(OH)₃(aq) + 2H₂O(l) → H₃O⁺(aq) + B(OH)₄⁻(aq) [Ka = 5.6 × 10⁻¹⁰] What is the pH of an eyewash solution which is 0.0018 M in boric acid? A) 3.75 B) 4.75 C) 6.00 D) 7.49 E) 9.25

C) 6.00

In seawater, Mg²⁺ is about 1350 mg Mg²⁺/L. How many grams of magnesium are in a pool that is 25 ft by 12 ft by 6 ft? (1 ft = 12 inches and 1 inch = 2.54 cm) A) 4.78 x 10² g B) 74.1 g C) 6.88 x 10⁴ g D) 6.88 x 10⁷ g E) 1.64 x 10³ g

C) 6.88 x 10⁴ g

Both gypsum and plaster of Paris contain the same compound, but in different stages of hydration. That compound is: A) BaSO₄ B) BaCO₃ C) CaSO₄ D) CaCO₃ E) KAl(SO₄)₂

C) CaSO₄

In the production of magnesium metal by the Dow process, the other immediate product of the electrolysis of the molten magnesium chloride is: A) H₂ (g) B) HCl (g) C) Cl₂ (g) D) MgO (s) E) Mg(OH)₂ (s)

C) Cl₂ (g)

Choose the INCORRECT statement. A) The strong C-C and C-H bonds are very important in organic chemistry B) At standard temperature and pressure graphite is more stable than diamond C) Graphite changes spontaneously but very slowly to diamond D) Pencil lead is a graphite and clay mixture E) No harder substance than diamond is known

C) Graphite changes spontaneously but very slowly to diamond

Choose the INCORRECT statement. A) Fluorine adopts the -1 oxidation state when it forms compounds. B) In binary compounds with metals, the oxidation state of halogens is -1. C) Halogen ions commonly exhibit a charge of +1. D) Iodine can have oxidation states of +1, +3, +5 and +7 in compounds where iodine is bonded to oxygen and/or fluorine. E) HClO is hypochlorous acid.

C) Halogen ions commonly exhibit a charge of +1.

Choose the incorrect statement about Na₂CO₃: A) A by-product from the production of Na₂CO₃ is CaCl₂, which has a useful application in some localities B) It is an important commercial compound used in the glass, soap, and paper industries C) It is produced by the Solvay process which utilizes NaCl and CaO as the primary raw materials in a multi-step synthesis D) It is mined from large deposits in western United States E) Sodium carbonate can be formed by heating sodium bicarbonate

C) It is produced by the Solvay process which utilizes NaCl and CaO as the primary raw materials in a multi-step synthesis

Which incorrectly shows the main product of reaction of the indicated alkali metal with excess oxygen? A) Li/Li₂O B) Na/Na₂O₂ C) K/K₂O₂ D) Rb/RbO₂ E) Cs/CsO₂

C) K/K₂O₂

Write the equation for the production of potassium metal from potassium chloride. A) KCl(s) + Na(s) → ⁴⁵⁰° NaCl(s) + K(s) B) KCl(s) + Na(s) →⁴⁵⁰° KNaCl(s) C) KCl(l) + Na(l) →⁸⁵⁰° NaCl(l) + K(g) D) KCl(l) + Na(g) →⁷⁵⁰° NaCl(s) + K(s) E) There is no reaction.

C) KCl(l) + Na(l) →⁸⁵⁰° NaCl(l) + K(g)

Complete the reaction: SiO₂ + 2C (+heat) → A) SiO + C₂O B) SiC + CO₂ C) Si + 2CO(g) D) SiCO + CO E) SiC₂O₂

C) Si + 2CO(g)

Which of the following has more than one allotrope? A) Pb B) Cd C) Sn D) Mg E) Al

C) Sn

Which of the following metals is refined by some means other than electrolysis? A) Na B) Mg C) Sn D) Al E) Zn

C) Sn

Choose the INCORRECT statement. A) Oleum is SO₃(g) dissolved in H₂SO₄. B) Oleum is called fuming sulfuric acid. C) Sulfuric and sulfurous acids are monoprotic. D) Acid salts are compounds formed from polyprotic acids by neutralizing one hydrogen. E) Thio in a name denotes that one oxygen is replaced by a sulfur.

C) Sulfuric and sulfurous acids are monoprotic.

Tl is different from Al, Ga, and In in that: A) Tl has a much different electronegativity B) Tl has a much different first ionization energy C) Tl commonly forms compounds with +1 oxidation state D) Tl forms metal hydroxides that are amphoteric E) Tl commonly forms compounds with +3 oxidation state

C) Tl commonly forms compounds with +1 oxidation state

Which of the following is found in Teflon, Freon-12, and in the acid commonly used to etch glass? A) carbon B) chlorine C) fluorine D) hydrogen E) oxygen

C) fluorine

Which of the following exists in more different allotropic forms than any other element? A) xenon B) tellurium C) sulfur D) phosphorus E) oxygen

C) sulfur

Choose the INCORRECT equation. A) CaO + 3C →CaC₂ + CO B) CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂ C) CH₄ + 4S → CS₂ + 2H₂S D) (CN)₂ + 2OH⁻ → 2HOCN E) CH₄ + 4Cl₂ → CCl₄ + 4HCl

D) (CN)₂ + 2OH⁻ → 2HOCN

Write the chemical equation for the reaction of potassium superoxide with carbon dioxide to produce oxygen. A) KO(s) + CO₂(g) → O₂(g) + K(s) + CO(g) B) K₂O(s) + CO₂(g) → O₂(g) + K(s) + KCO(s) C) KO₂ + CO₂(g) → 2O₂(g) + KC(s) D) 2KO₂(s) + 2CO₂(g) → K₂CO₃(s) + O₂(g) E) There is no reaction.

D) 2KO₂(s) + 2CO₂(g) → K₂CO₃(s) + O₂(g)

Finish the following reaction: Li(s) + N₂(g) → A) 3Li(s) + N₂(g) → Li₃N₂(s) B) 4Li(s) + N₂(g) → 2Li₂N(s) C) 2Li(s) + N₂(g) → 2LiN(s) D) 6Li(s) + N₂(g) → Li₃N(s) E) There is no reaction

D) 6Li(s) + N₂(g) → Li₃N(s)

Choose the INCORRECT statement. A) Graphite and diamond are two allotropes of carbon. B) Graphite can be used as a lubricant because sheets of graphite slide over other sheets of graphite. C) Carbon black is finely divided soot used in tires, inks and pigments. D) All carbon containing compounds are the subject of inorganic chemistry. E) Certain groupings of atoms which have the characteristics of a halogen atom are called psuedohalogens.

D) All carbon containing compounds are the subject of inorganic chemistry.

Complete the following reaction: B(OH)₃(aq) + 2H₂O(l) → A) B · H₂O + O₂ + H₃O⁺ B) HBO₃²⁻ + 2H₃O⁺ C) B + H₂ + 5OH⁻ D) H₃O⁺ + B(OH)₄⁻ E) 2H₃O⁺ + HBO₃

D) H₃O⁺ + B(OH)₄⁻

Choose the INCORRECT statement. A) Compounds with xenon in several oxidation states have been formed. B) The eight outer shell electrons cause chemical inertness. C) Xenon reacts directly only with fluorine. D) Noble gases exist as diatomic molecules. E) Most noble gas compounds contain either fluorine or oxygen.

D) Noble gases exist as diatomic molecules.

Choose Incorrect Statement: A) Sodium bicarbonate is sodium hydrogen carbonate B) O₂²⁻ occurs in a peroxide C) O₂²⁻ occurs in a superoxide D) The hydroxides of alkali metals are amphoteric E) Alkali metal hydroxides can be used to make soaps and detergents

D) The hydroxides of alkali metals are amphoteric

Which of the following compounds is invoked to demonstrate the inert-pair effect? A) Al(OH)₃ B) GaAs C) InAs D) Tl₂O E) Al₂O₃

D) Tl₂O

Iodine is only very slightly soluble in water, but it dissolves readily in an aqueous solution of sodium iodide, because molecular iodine acts as: A) a Lewis base to form a coordinate covalent bond with Na⁺ ion B) a reducing agent with water, to form the soluble I⁺ ion C) an oxidizing agent with I⁻ ion to form the soluble I₃⁺ ion D) a Lewis acid to form a coordinate covalent bond with I⁻ ion E) a catalyst for the disproportionation of water

D) a Lewis acid to form a coordinate covalent bond with I⁻ ion

Choose the INCORRECT name/formula combination. A) ozone / O₃ B) potassium superoxide / KO₂ C) dioxygen / O₂ D) carbon monoxide / C₂O E) trioxygen / O₃

D) carbon monoxide / C₂O

The molecular geometry for CO2 is ________. A) trigonal planar B) trigonal bipyramid C) bent D) linear E) trigonal pyramidal

D) linear

The molecular geometry for HCN is ________. A) trigonal planar B) trigonal bipyramid C) bent D) linear E) trigonal pyramidal

D) linear

Quartz and mica are examples of: A) silanols B) silanes C) silicones D) silicates E) isomers

D) silicates

HI(g) has a ΔGf° that is small and positive, so HI should dissociate to some extent but its activation energy is high. HI(g) is stable at room temperature. Chemists would describe the reason for the very slow dissociation reaction as: A) thermodynamically controlled B) the ΔGf° is wrong C) the reaction is not slow D) the reaction is kinetically controlled E) the molecules can collide with each other

D) the reaction is kinetically controlled

The Ka for boric acid is 5.6 × 10⁻¹⁰. What is the pH for 0.10 sodium borate? A) 8.87 B) 5.13 C) 5.75 D) 2.87 E) 11.13

E) 11.13

he production of lead is a two step process: 2PbS(s) + 3O₂(g) (+heat)→ 2PbO(s) + 2SO₂(g) 2PbO(s) + C(s) (+heat)→ 2Pb(l) + CO₂(g) How much ore that is 5.2% PbS is necessary to produce 12.0 kg of Pb? A) 0.721 kg B) 200 kg C) 2.67 kg D) 133 kg E) 267 kg

E) 267 kg

Bronze is 90% Cu and 10% Sn by mass. What is the density of bronze if the density of Cu is 8.95 g/cm³ and the density of Sn is 5.77 g/cm³? A) 7.36 B) 6.07 C) 8.06 D) 14.72 E) 8.63

E) 8.63

In the production of the metal by an electrolysis process, which of the following is the most costly in terms of amount of electricity required per ton of metal produced from its salt? A) Na B) Mg C) Cu D) Ba E) Al

E) Al

Which of the following is an indication that aluminum is a strong reducing agent? A) 2Al(s) + 6H⁺ → 2Al³⁺(aq) + 3H₂(g) B) 2Al(s) + Fe₂O₃(s) → Al₂O₃(s) + 2 Fe(l) C) 2Al(s) + 3/2 O₂(g) → Al₂O₃(s) ΔH = -1676 kJ D) 2Al(s) + 2OH⁻ + 6H₂O(l) → 2[Al(OH)₄]⁻(aq) + 3H₂(g) E) All of these reactions indicate Al is a strong reducing agent.

E) All of these reactions indicate Al is a strong reducing agent.

Using VSEPR theory, which of the following descriptions of probable molecular geometry is INCORRECT? A) SF₆/octahedral B) SiCl₄/tetrahedral C) BF₃/trigonal planar D) SnCl₄/tetrahedral E) ClF₃/pyramidal

E) ClF₃/pyramidal

Choose the INCORRECT statement about carbon. A) In addition to diamonds and graphite, fullerenes and nanotubes are allotropes B) The finely divided soot from an incomplete combustion of natural gas is called carbon black C) Coke is the result of heating coal in the absence of air D) Charcoal is the result of heating wood in the absence of air E) Diamond is an excellent conductor

E) Diamond is an excellent conductor

Choose the INCORRECT statement. A) Chlorofluorocarbon production has been banned by many countries. B) Chlorine is used to make bleach, PVC, treat water, and make chemicals. C) Bromine is used in fire retardants, pesticides, dyes, pharmaceuticals, and film. D) Iodine is used in catalysts, medicine and film. E) Fluorinated organic compounds are very reactive.

E) Fluorinated organic compounds are very reactive.

Choose the INCORRECT statement. A) Halogens exist as diatomic molecules. B) Group 17 (7A) are the halogens. C) Halogens have relatively low melting and boiling points. D) Fluorine is the most reactive halogen. E) Fluorine has a low electronegativity and large radius.

E) Fluorine has a low electronegativity and large radius.

Choose the INCORRECT statement. A) Perbromic acid is HBrO₄. B) Bromite ion is BrO₂⁻. C) Iodate ion is IO₃⁻. D) Hypochlorite ion is ClO⁻. E) Hydrochloric acid is HClO₂.

E) Hydrochloric acid is HClO₂

Choose the INCORRECT name/symbol combination. A) Xe Xenon B) Ne Neon C) Kr Krypton D) Ar Argon E) Ra Radon

E) Ra Radon

Choose the INCORRECT statement. A) A glass is an amorphous solid. B) An amorphous solid has order over relatively short distances. C) A sol is a colloidal dispersion of particles in a liquid. D) Silicones are materials consisting of molecules with long silicon-oxygen chains. E) Silicates are silicon-hydrogen containing compounds.

E) Silicates are silicon-hydrogen containing compounds.

Which of the following has the highest boiling point? A) bromine B) chlorine C) fluorine D) iodine E) astatine

E) astatine

Which of the following metals has been used commercially in certain drain cleaners, along with solid sodium hydroxide, for the purpose of generating hydrogen gas by reaction with hydroxide ion after contact with water? A) Al B) Ba C) Cu D) Fe E) Ge

A) Al

Which oxidation state is uncommon for a given element? A) Al/1+ B) Ga/3+ C) Al/3+ D) In/3+ E) In/1+

A) Al/1+

Choose the INCORRECT statement. A) Argon forms compounds readily. B) Argon, xenon, krypton, neon, helium, and radon are called noble gases. C) Liquid helium is used to maintain low temperatures. D) Metals that lose their electrical resistivity are called superconductors. E) Radon is a radioactive element.

A) Argon forms compounds readily.

Choose the INCORRECT statement. A) By electrode potentials, fluorine is the least reactive halogen. B) Chlorine is prepared industrially by the electrolysis of NaCl. C) Fluorine is usually prepared by electrolysis. D) Bromine can be extracted from seawater. E) Iodine is obtained commercially from inland brines or from sodium iodate deposits.

A) By electrode potentials, fluorine is the least reactive halogen.

Choose the INCORRECT statement about carbon. A) Carbon does not form multiple bonds. B) There are two very common allotropes: diamond and graphite. C) There is a strong tendency for catenation. D) Carbon can be hybridized into sp, sp² and sp³ orbitals. E) Carbon primarily forms two gaseous oxides: CO and CO₂.

A) Carbon does not form multiple bonds.

Which of these is the strongest oxidizing agent? A) HClO₂ B) HClO₃ C) HClO₄ D) KClO₃ E) KClO₂

A) HClO₂

Choose the INCORRECT statement. A) H₂O has a high boiling point because of covalent bonding. B) Sulfur can form S₈ molecules. C) Compounds with O-O bonds are reactive. D) H₂O is a bent molecule. E) H₂O is a polar molecule.

A) H₂O has a high boiling point because of covalent bonding

The Frasch process for the production of elemental sulfur has been largely supplanted by a gas- phase process using the reduction of sulfur dioxide by: A) H₂S(g) B) H₂O(g) C) CS₂(g) D) H₂SO₄(g) E) O₃(g)

A) H₂S(g)

The VSEPR theory predicts molecular shapes for the noble gas compounds. Which of these is correct? I) XeF2 is linear. II) XeOF2 is T-shaped. III) XeF4 is square planar. A) I, II and III B) I and II C) I only D) II only E) III only

A) I, II and III

When sodium and potassium react with excess oxygen, the major products are: A) Na₂O₂ and KO₂ B) NaO₂ and KO₂ C) Na₂O and KO₂ Na₂O₂ and K₂O₂

A) Na₂O₂ and KO₂

Finish the following reaction: SnO₂ +NaOH(aq)→ A) SnO₂(s) + 2NaOH + 2H₂O → Na₂Sn(OH)₆ B)SnO₂(s) + 2NaOH + 2H₂O → Sn(OH)₂ + 2NaO + 2H₂O C) SnO₂(s) + 2NaOH + 2H₂O → Sn(OH)₄ + 2NaO + H₂ D) SnO₂(s) + 2NaOH + 2H₂O → Sn(OH)₂ + 2Na + H₂O₂ E) There is no reaction

A) SnO₂(s) + 2NaOH + 2H₂O → Na₂Sn(OH)₆

Choose Incorrect Statement: A) The class "detergents" does not include soaps B) Detergents are cleansing agents C) Detergents emulsify oils D) Detergents usually mean synthetic products E) A soap is a salt of a metal hydroxide and a fatty acid

A) The class "detergents" does not include soaps

For which of the following elements would be wrong to call the oxide "amphoteric"? A) Tl. B) Al. C) Be. D) Ga.

A) Tl.

Graphite and diamond are: A) allotropes B) amorphous substances C) bivalent D) elastomers E) very unstable

A) allotropes

Ozone and "ordinary" oxygen are examples of: A) allotropes B) isotopes C) isomers D) phalaropes E) tropomers

A) allotropes

What is one of the important uses of KClO₄? A) explosives B) adhesives C) lubricants D) metal finishing E) skin cleaning

A) explosives

Predict the shape of cyanogen, (CN)₂. A) linear B) bent C) tetrahedral D) trigonal pyramidal

A) linear

"Halogen" means "soluble salts".

False

A magnesium fire can always be extinguished with carbon dioxide

False

Both bismuth and arsenic are obtained from their sulfide ores

False

Hydrogen bonded with any metals form compounds called ionic hydrides

False

Hydrogen compounds are called hybrids

False

Hydrogen peroxide may act only as an oxidizing agent

False

In a nonmetal hydroxide the oxygen-hydrogen bond is generally less polar than the nonmetal-oxygen bond

False

Metal oxides generally form an acidic solution in water

False

Selenium is obtained by the Frasch process.

False

Strontium is a softer metal than calcium

False

The first ionization potential of calcium is smaller than that of strontium

False

The noble gas Xe is completely unreactive

False

Halogen molecules are diatomic

True

Nitrogen is obtained from air by fractional distillation

True

Oxygen is obtained commercially from air by fractional distillation

True

Strontium hydroxide is classified as "basic"

True

Strontium hydroxide is more soluble in water than is calcium hydroxide

True

The atomic radius of calcium is smaller than that of strontium

True

The chemistry of Be is different from that of the other group 2 metals due to the small size of Be²⁺

True

The noble gas Xe is obtained commercially from air by fractional distillation.

True