Chapter 1

Molecular mass of dry air is (a) less than moist air (b) greater than moist air (c) equal to moist air (d) may be greater or less than moist air

A sample of iron oxide has \(\mathrm{FeO}\) and \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) in the mole ratio \(2: 1\). It is partially oxidized to change this ratio to \(1: 2\). The number of moles of \(\mathrm{FeO}\) oxidized per mole of initial mixture is (a) \(0.2\) (b) \(0.333\) (c) \(0.4\) (d) \(0.5\)

A gaseous mixture contains \(70 \% \mathrm{~N}\), and \(30 \%\) unknown gas, by volume. If the average molecular mass of gaseous mixture is \(37.60\), the molecular mass of unknown gas is (a) \(42.2\) (b) 60 (c) 40 (d) 50

An amount of 1 mole of calcium cyanamide and 1 mole of water are allowed to react. The number of moles of ammonia produced is (a) \(3.0\) (b) \(2.0\) (c) \(1.0\) (d) \(0.67\)

The mass composition of universe may be given as \(90 \% \mathrm{H}_{2}\) and \(10 \%\) He. The average molecular mass of universe should be (a) \(2.20\) (b) \(2.10\) (c) \(3.80\) (d) \(3.64\)

Cyclohexanol is dehydrated to cyclohexene on heating with conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\). If the yield of this reaction is \(75 \%\), how much cyclohexene will be obtained from \(100 \mathrm{~g}\) of cyclohexanol? (a) \(61.5 \mathrm{~g}\) (b) \(82 \mathrm{~g}\) (c) \(109.3 \mathrm{~g}\) (d) \(75 \mathrm{~g}\)

A sample of pure Cu \((4.00 \mathrm{~g})\) heated in a stream of oxygen for some time, gains in weight with the formation of black oxide of copper \((\mathrm{CuO})\). The final mass is 4.90 g. What per cent of copper remains unoxidized? \((\mathrm{Cu}=64)\) (a) \(90 \%\) (b) \(10 \%\) (c) \(20 \%\) (d) \(80 \%\)

If the yield of chloroform obtainable from acetone and bleaching powder is \(75 \%\), what mass of acetone is required for producing \(30 \mathrm{~g}\) of chloroform? (a) \(40 \mathrm{~g}\) (b) \(9.4 \mathrm{~g}\) (c) \(10.92 \mathrm{~g}\) (d) \(14.56 \mathrm{~g}\)

The commonly used pain reliever, aspirin, has the molecular formula \(\mathrm{C}_{2} \mathrm{H}_{8} \mathrm{O}_{4}\). If a sample of aspirin contains \(0.968 \mathrm{~g}\) of carbon, what is the mass of hydrogen in the sample? (a) \(0.717 \mathrm{~g}\) (b) \(0.0717 \mathrm{~g}\) (c) \(8.000 \mathrm{~g}\) (d) \(0.645 \mathrm{~g}\)

Pure \(\mathrm{FeS}_{2}\) is burnt with \(60 \%\) excess air. What is the percentage of \(\mathrm{N}_{2}\), by volume, in the gaseous mixture after the reaction? Air contains \(20 \% \mathrm{O}_{2}\) and \(80 \% \mathrm{~N}_{2}\), by volume. (a) \(81.94\) (b) \(82.8\) (c) \(8.2\) (d) \(89.3\)

For \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\), which is the correct mole relationship? (a) \(9 \times\) mole of \(\mathrm{Cu}=\) mole of \(\mathrm{O}\) (b) \(5 \times\) mole of \(\mathrm{Cu}=\) mole of \(\mathrm{O}\) (c) \(9 \times\) mole of \(\mathrm{Cu}=\) mole of \(\mathrm{O}_{2}\) (d) mole of \(\mathrm{Cu}=5 \times \mathrm{mole}\) of \(\mathrm{O}\)

A quantity of \(5 \mathrm{~g}\) of a crystalline salt when rendered anhydrous lost \(1.8 \mathrm{~g}\) of water. The formula mass of the anhydrous salt is 160 . The number of molecules of water of crystallization in the salt is (a) 3 (b) 5 (c) 2 (d) 1

Cortisone is a molecular substance containing 21 atoms of carbon per molecule. The mass percentage of carbon in cortisone is \(69.98 \%\). What is the molecular mass of cortisone? (a) \(180.05\) (b) \(360.1\) (c) \(312.8\) (d) \(205.8\)

A mixture is made equal volume of \(\mathrm{CO}\) and air. A spark passed through so that all the oxygen is converted to carbon dioxide. What will be fractional decrease in the total volume of system assuming pressure and temperature remain constant? Air contains \(20 \%\) oxygen by volume. (a) \(0.1\) (b) \(0.2\) (c) \(0.15\) (d) \(0.3\)

A polystyrene of formula \(\mathrm{Br}_{3} \mathrm{C}_{6} \mathrm{H}_{2}\left(\mathrm{C}_{8} \mathrm{H}_{8}\right)_{n}\) was prepared by heating styrene with tribromobenzyl peroxide in the absence of air. It was found to contain \(10.46 \%\) bromine, by mass. The value of \(n\) is \((\mathrm{Br}=80)\) (a) 20 (b) 21 (c) 19 (d) 22

The percentage of oxygen in a compound is \(4 \%\). Its minimum molecular mass will be (a) 100 (b) 400 (c) 200 (d) 32

In Dumas method, \(0.2 \mathrm{~g}\) of an organic nitrogenous compound gave \(28 \mathrm{ml}\) of \(\mathrm{N}_{2}\) (volume reduced to \(0^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\) ). What is the percentage of nitrogen, by mass, in the compound? (a) \(17.5\) (b) \(8.75\) (c) \(35.0\) (d) \(14.0\)

When \(V \mathrm{ml}\) of \(2.2 \mathrm{M}-\mathrm{H}_{2} \mathrm{SO}_{4}\) solution is mixed with \(10 \mathrm{~V} \mathrm{ml}\) of water, the volume contraction of \(2 \%\) takes place. The molarity of diluted solution is (a) \(0.2 \mathrm{M}\) (b) \(0.204 \mathrm{M}\) (c) \(0.196 \mathrm{M}\) (d) \(0.224 \mathrm{M}\)

A quantity of \(0.2 \mathrm{~g}\) of an organic compound containing, \(\mathrm{C}, \mathrm{H}\) and \(\mathrm{O}\), on combustion yielded \(0.147 \mathrm{~g} \mathrm{CO}_{2}\) and \(0.12 \mathrm{~g}\) water. The percentage of oxygen in it is (a) \(73.29 \%\) (b) \(78.45 \%\) (c) \(83.23 \%\) (d) \(89.50 \%\)

The empirical formula of an organic gaseous compound containing carbon and hydrogen is \(\mathrm{CH}_{2}\). The volume occupied by certain mass of this gas is exactly half of the volume occupied by the same mass of nitrogen gas under identical conditions. The molecular formula of the organic gas is (a) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (b) \(\mathrm{CH}_{2}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{12}\) (d) \(\mathrm{C}_{4} \mathrm{H}_{8}\)

Chlorofluorocarbons such as \(\mathrm{CCl}_{3} \mathrm{~F}\) \((\mathrm{M}=137.5)\) and \(\mathrm{CCl}_{2} \mathrm{~F}_{2}(\mathrm{M}=121)\) have been linked to ozone depletion in Antarctica. As of 2004 , these gases were found in 275 and 605 parts per trillion \(\left(10^{12}\right)\), by volume. What are the concentrations of these gases under conditions typical of Antarctica stratosphere \((200 \mathrm{~K}\) and \(0.08 \mathrm{~atm}) ?(R=0.081-\mathrm{atm} / \mathrm{K}-\mathrm{mol})\) (a) \(\left[\mathrm{CCl}_{3} \mathrm{~F}\right]=1.375 \times 10^{-12} \mathrm{~mol} \mathrm{1}^{-1}\), \(\left[\mathrm{CCl}_{2} \mathrm{~F}_{2}\right]=3.025 \times 10^{-12} \mathrm{~mol} 1^{-1}\) (b) \(\left[\mathrm{CCl}_{3} \mathrm{~F}\right]=2.75 \times 10^{-14} \mathrm{~mol} 1^{-1},\left[\mathrm{CCl}_{2} \mathrm{~F}_{2}\right]\) \(=6.05 \times 10^{-14} \mathrm{~mol} 1^{-1}\) (c) \(\left[\mathrm{CCl}_{3} \mathrm{~F}\right]=2.75 \times 10^{-10} \mathrm{~mol} 1^{-1},\left[\mathrm{CCl}_{2} \mathrm{~F}_{2}\right]\) \(=6.05 \times 10^{-10} \mathrm{~mol} 1^{-1}\) (d) \(\left[\mathrm{CCl}_{3} \mathrm{~F}\right]=1.375 \times 10^{-13} \mathrm{~mol} \mathrm{H}^{-1}\), \(\left[\mathrm{CCl}_{2} \mathrm{~F}_{2}\right]=3.025 \times 10^{-12} \mathrm{~mol} 1^{-1}\)

A compound having the empirical formula, \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}\), has a molecular weight of \(170 \pm 5\). The molecular formula of the compound is (a) \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{2}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{3}\) (d) \(\mathrm{C}_{9} \mathrm{H}_{12} \mathrm{O}_{3}\)

It was found from the chemical analysis of a gas that it has two hydrogen atoms for each carbon atom. At \(0^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\), its density is \(1.25 \mathrm{~g}\) per litre. The formula of the gas would be (a) \(\mathrm{CH}_{2}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{6}\) (d) \(\mathrm{C}_{4} \mathrm{H}_{8}\)

A quantity of \(500 \mathrm{~g}\) of a urea solution of mole fraction \(0.2\) is diluted to \(1500 \mathrm{~g}\). The mole fraction of solute in the diluted solution is (a) \(0.05\) (b) \(0.067\) (c) \(0.6\) (d) \(0.1\)

A volume of \(50 \mathrm{ml}\) of ' 20 vol' \(\mathrm{H}_{2} \mathrm{O}_{2}\) solution is mixed with \(50 \mathrm{ml}\) of ' 10 vol' \(\mathrm{H}_{2} \mathrm{O}_{2}\) solution. The volume strength of resulting solution is (assume neither expansion nor contraction in volume of solution, on mixing) (a) ' 30 vol' (b) '10 vol' (c) '15 vol' (d) \(22.5\) vol'

A compound contains elements \(\mathrm{X}\) and \(\mathrm{Y}\) in \(1: 4\) mass ratio. If the atomic masses of \(X\) and \(Y\) are in \(1: 2\) ratio, the empirical formula of compound should be (a) \(\mathrm{XY}_{2}\) (b) \(\mathrm{X}_{2} \mathrm{Y}\) (c) XY \(_{4}\) (d) \(\mathrm{X}_{4} \mathrm{Y}\)

A compound contains equal masses of the elements \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\). If the atomic masses of \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) are 20,40 and 60 , respectively, the empirical formula of the compound is (a) \(\mathrm{A}_{3} \mathrm{~B}_{2} \mathrm{C}\) (b) \(\mathrm{AB}_{2} \mathrm{C}_{3}\) (c) \(\mathrm{ABC}\) (d) \(\mathrm{A}_{6} \mathrm{~B}_{3} \mathrm{C}_{2}\)

Samples of \(1.0 \mathrm{~g}\) of \(\mathrm{Al}\) are treated separately with an excess of sulphuric acid and an excess of sodium hydroxide. The ratio of the number of moles of the hydrogen gas evolved is (a) \(1: 1\) (b) \(3: 2\) (c) \(2: 1\) (d) \(9: 4\)

An ore contains \(2.296 \%\) of the mineral argentite, \(\mathrm{Ag}_{2} \mathrm{~S}\), by mass. How many grams of this ore would have to be processed in order to obtain \(1.00 \mathrm{~g}\) of pure solid silver? \((\mathrm{Ag}=108)\) (a) \(1.148 \mathrm{~g}\) (b) \(0.026 \mathrm{~g}\) (c) \(50 \mathrm{~g}\) (d) \(2.296 \mathrm{~g}\)

An amount of \(1.0 \times 10^{-3}\) moles of \(\mathrm{Ag}^{+}\) and \(1.0 \times 10^{-3}\) moles of \(\mathrm{CrO}_{4}^{2-}\) reacts together to form solid \(\mathrm{Ag}_{2} \mathrm{CrO}_{4}\). What is the amount of \(\mathrm{Ag}_{2} \mathrm{CrO}_{4}\) formed? \((\mathrm{Ag}=108, \mathrm{Cr}=52)\) (a) \(0.332 \mathrm{~g}\) (b) \(0.166 \mathrm{~g}\) (c) \(332 \mathrm{~g}\) (d) \(166 \mathrm{~g}\)

An amount of \(0.3 \mathrm{~mole}\) of \(\mathrm{SrCl}_{2}\) is mixed with \(0.2\) mole of \(\mathrm{K}_{3} \mathrm{PO}_{4}\). The maximum moles of \(\mathrm{KCl}\) which may form is (a) \(0.6\) (b) \(0.5\) (c) \(0.3\) (d) \(0.1\)

Hydrogen cyanide, HCN, is prepared from ammonia, air and natural gas \(\left(\mathrm{CH}_{4}\right)\) by the following process. \(2 \mathrm{NH}_{3}(\mathrm{~g})+3 \mathrm{O}_{2}(\mathrm{~g})+2 \mathrm{CH}_{4}(\mathrm{~g}) \stackrel{\mathrm{P}_{t}}{\longrightarrow}\) \(2 \mathrm{HCN}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})\) If a reaction vessel contains \(11.5 \mathrm{~g} \mathrm{NH}_{3}\), \(10.0 \mathrm{~g} \mathrm{O}_{2}\), and \(10.5 \mathrm{~g} \mathrm{CH}_{4}\), what is the maximum mass, in grams, of hydrogen cyanide that could be made, assuming the reaction goes to completion? (a) \(18.26 \mathrm{~g}\) (b) \(5.625 \mathrm{~g}\) (c) \(17.72 \mathrm{~g}\) (d) \(16.875 \mathrm{~g}\)

What mass of carbon disulphide, \(\mathrm{CS}_{2}\) can be completely oxidized to \(\mathrm{SO}_{2}\) and \(\mathrm{CO}_{2}\) by the oxygen liberated when \(325 \mathrm{~g}\) of \(\mathrm{Na}_{2} \mathrm{O}_{2}\) react with water? (a) \(316.67 \mathrm{~g}\) (b) \(52.78 \mathrm{~g}\) (c) \(633.33 \mathrm{~g}\) (d) \(211.11 \mathrm{~g}\)

A quantity of \(4.35 \mathrm{~g}\) of a sample of pyrolusite ore, when heated with conc. HCl, gave chlorine. The chlorine, when passed through potassium iodide solution, liberated \(6.35 \mathrm{~g}\) of iodine. The percentage of pure \(\mathrm{MnO}_{2}\) in the pyrolusite ore is \((\mathrm{Mn}=55, \mathrm{I}=127)\) (a) 40 (b) 50 (c) 60 (d) 70

A quantity of \(10 \mathrm{~g}\) of a piece of marble was put into excess of dilute \(\mathrm{HCl}\) acid. When the reaction was complete, \(1120 \mathrm{~cm}^{3}\) of \(\mathrm{CO}_{2}\) was obtained at \(0^{\circ} \mathrm{C}\) and 1 atm. The percentage of \(\mathrm{CaCO}_{3}\) in the marble is (a) \(5 \%\) (b) \(25 \%\) (c) \(50 \%\) (d) \(2.5 \%\)

Two successive reactions, \(\mathrm{A} \rightarrow \mathrm{B}\) and \(\mathrm{B} \rightarrow \mathrm{C}\), have yields of \(90 \%\) and \(80 \%\), respectively. What is the overall percentage yield for conversion of \(\mathrm{A}\) to \(\mathrm{C}\) ? (a) \(90 \%\) (b) \(80 \%\) (c) \(72 \%\) (d) \(85 \%\)

Iodobenzene is prepared from aniline \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}\right)\) in a two-step process as shown here: \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}+\mathrm{HNO}_{2}+\mathrm{HCl} \longrightarrow\) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}^{+} \mathrm{Cl}^{-}+2 \mathrm{H}_{2} \mathrm{O}\) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}^{+} \mathrm{Cl}^{-}+\mathrm{KI} \rightarrow \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{I}+\mathrm{N}_{2}+\mathrm{KCl}\) In an actual preparation, \(9.30 \mathrm{~g}\) of aniline was converted to \(16.32 \mathrm{~g}\) of iodobenzene. The percentage yield of iodobenzene is \((\mathrm{I}=127)\) (a) 8\% (b) \(50 \%\) (c) \(75 \%\) (d) \(80 \%\)

The explosion of a mixture consisting of one volume of a gas being studied and one volume of \(\mathrm{H}_{2}\) yielded one volume water vapour and one volume of \(\mathrm{N}_{2}\). The formula of gas being studied, is (a) \(\mathrm{NO}\) (b) \(\mathrm{NO}_{2}\) (c) \(\mathrm{N}_{2} \mathrm{O}\) (d) \(\mathrm{N}_{2} \mathrm{O}_{3}\)

A gaseous alkane is exploded with oxygen. The volume of \(\mathrm{O}_{2}\), for complete combustion to the volume of \(\mathrm{CO}_{2}\) formed is in 7:4 ratio. The molecular formula of alkane is (a) \(\mathrm{CH}_{4}\) (b) \(\mathrm{C}_{3} \mathrm{H}_{8}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{6}\) (d) \(\mathrm{C}_{4} \mathrm{H}_{10}\)

An aqueous solution of glucose is \(10 \%\) \((\mathrm{w} / \mathrm{v})\). The volume in which \(1 \mathrm{~mole}\) of glucose is dissolved, will be (a) 181 (b) 91 (c) \(0.91\) (d) \(1.81\)

How much \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\), in \(\mathrm{mg}\), must be present in \(50 \mathrm{ml}\) of a solution with \(2.35\) ppm of Ca? (a) \(0.1175\) (b) \(770.8\) (c) \(4.7\) (d) \(0.48\)

The legal limit for human exposure to \(\mathrm{CO}\) in the work place is 35 ppm. Assuming that the density of air is \(1.3 \mathrm{~g} / 1\), how many grams of \(\mathrm{CO}\) are in \(1.0 \mathrm{l}\) of air at the maximum allowable concentration? (a) \(4.55 \times 10^{-5} \mathrm{~g}\) (b) \(3.5 \times 10^{-5} \mathrm{~g}\) (c) \(2.69 \times 10^{-5} \mathrm{~g}\) (d) \(7.2 \times 10^{-5} \mathrm{~g}\)

D5W refers to one of the solutions used as an intravenous fluid. It is a \(5 \%\) by mass solution of dextrose, \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) in water. The density of \(\mathrm{D} 5 \mathrm{~W}\) is \(1.08 \mathrm{~g} / \mathrm{ml}\). The molarity of the solution is (a) \(0.3 \mathrm{M}\) (b) \(0.6 \mathrm{M}\) (c) \(0.28 \mathrm{M}\) (d) \(0.26 \mathrm{M}\)

How much \(\mathrm{BaCl}_{2}\) would be needed to make \(250 \mathrm{ml}\) of a solution having the same concentration of \(\mathrm{Cl}^{-}\) as one containing \(\begin{array}{llll}3.78 & \mathrm{~g} & \mathrm{NaCl} \text { per } 100 \mathrm{ml} \text { ? }\end{array}\) \((\mathrm{Ba}=137)\) (a) \(16.8 \mathrm{~g}\) (b) \(67.2 \mathrm{~g}\) (c) \(33.6 \mathrm{~g}\) (d) \(22.4 \mathrm{~g}\)

A volume of \(500 \mathrm{ml}\) of a \(0.1 \mathrm{M}\) solution of \(\mathrm{AgNO}_{3}\) added to \(500 \mathrm{ml}\) of \(0.1 \mathrm{M}\) solution of \(\mathrm{KCl}\). The concentration of nitrate ion in the resulting solution is (a) \(0.05 \mathrm{M}\) (b) \(0.1 \mathrm{M}\) (c) \(0.2 \mathrm{M}\) (d) Reduced to zero

In \(1200 \mathrm{~g}\) solution, \(12 \mathrm{~g}\) urea is present. If density of the solution is \(1.2 \mathrm{~g} / \mathrm{ml}\), then the molarity of the solution is (a) \(0.2 \mathrm{M}\) (b) \(10 \mathrm{M}\) (c) \(0.167 \mathrm{M}\) (d) \(12 \mathrm{M}\)

A quantity of \(10 \mathrm{~g}\) of acetic acid is dissolved in \(100 \mathrm{~g}\) of each of the following solvents. In which solvent, the mole fraction of solute is maximum? Assume no any dissociation or association of acetic acid in the solvent. (a) Water (b) Ethanol (c) Benzene (d) Same in all solvents

An aqueous solution has urea and glucose in mass ratio \(3: 1\). If the mass ratio of water and glucose in the solution is \(10: 1\), then the mole fraction of glucose in the solution is (a) \(\frac{1}{110}\) (b) \(\frac{9}{110}\) (c) \(\frac{3}{110}\) (d) \(\frac{100}{110}\)

What is the percentage of 'free \(\mathrm{SO}_{3}^{\prime}\) in a sample of oleum labelled as '104.5\%'? (a) \(20 \%\) (b) \(40 \%\) (c) \(60 \%\) (d) \(80 \%\)