Chapter 1

A sample of clay contains \(50 \%\) silica and \(10 \%\) water. The sample is partially dried by which it loses \(8 \mathrm{~g}\) water. If the percentage of silica in the partially dried clay is 52 , what is the percentage of water in the partially dried clay? (a) \(2.0 \%\) (b) \(6.4 \%\) (c) \(10.4 \%\) (d) \(2.4 \%\)

A quantity of \(10 \mathrm{~g}\) of a hydrocarbon exactly requires \(40 \mathrm{~g}\) oxygen for complete combustion. The products formed are \(\mathrm{CO}_{2}\) and water. When \(\mathrm{CO}_{2}\) gas formed is absorbed completely in lime water, the mass of solution increases by \(27.5 \mathrm{~g}\). What is the mass of water formed in combustion? (a) \(22.5 \mathrm{~g}\) (b) \(27.5 \mathrm{~g}\) (c) \(50 \mathrm{~g}\) (d) \(10 \mathrm{~g}\)

When a mixture of aluminium powder and iron (III) oxide is ignited, it produces molten iron and aluminium oxide. In an experiment, \(5.4 \mathrm{~g}\) of aluminium was mixed with \(18.5 \mathrm{~g}\) of iron (III) oxide. At the end of the reaction, the mixture contained \(11.2 \mathrm{~g}\) of iron, \(10.2 \mathrm{~g}\) of aluminium oxide, and an undetermined amount of unreacted iron (III) oxide. No aluminium was left. What is the mass of the iron (III) oxide left? (a) \(2.5 \mathrm{~g}\) (b) \(7.3 \mathrm{~g}\) (c) \(8.3 \mathrm{~g}\) (d) \(2.9 \mathrm{~g}\)

Assume that sodium atoms are spheres of radius \(0.2 \mathrm{~nm}\) and that they are lined up side by side. How many miles, in length, is the line of atoms present in a \(1.15 \mathrm{mg}\) sample of sodium? \(\left(N_{\mathrm{A}}=6 \times 10^{23}\right)\) (a) \(1.2 \times 10^{10}\) (b) \(1.2 \times 10^{8}\) (c) \(7.5 \times 10^{8}\) (d) \(7.5 \times 10^{6}\)

Some bottles of colourless liquids were being labelled when the technicians accidentally mixed them up and lost track of their contents. A \(15.0 \mathrm{ml}\) sample withdrawn from one bottle weighed \(22.3 \mathrm{~g} .\) The technicians knew that the liquid was either acetone, benzene, chloroform on carbon tetrachloride(which have densities of \(0.792 \mathrm{~g} / \mathrm{cm}^{3}, 0.899 \mathrm{~g} / \mathrm{cm}^{3}, 1.489 \mathrm{~g} / \mathrm{cm}^{3}\), and \(1.595 \mathrm{~g} / \mathrm{cm}^{3}\), respectively). What was the identity of the liquid? (a) Carbon tetrachloride (b) Acetone (c) Chloroform (d) Benzene

A sample of an ethanol-water solution has a volume of \(55.0 \mathrm{~cm}^{3}\) and a mass of \(50.0 \mathrm{~g}\). What is the percentage of ethanol (by mass) in the solution? Assume that there is no change in volume when the pure compounds are mixed. The density of ethanol is \(0.80 \mathrm{~g} / \mathrm{cm}^{3}\) and that of water is \(1.00 \mathrm{~g} / \mathrm{cm}^{3}\). (a) \(20 \%\) (b) \(40 \%\) (c) \(60 \%\) (d) \(45.45 \%\)

The average density of the universe as a whole is estimated as \(3 \times 10^{-29} \mathrm{~g} / \mathrm{ml}\). If we assume that the entire mass is only \(\mathrm{H}\) atoms, what is the average volume of space that contains one \(\mathrm{H}\) atom? (a) \(111.111\) (b) \(1.8 \times 10^{-5} 1\) (c) \(55.561\) (d) \(3.6 \times 10^{-5} 1\)

In a textile mill, a double-effect evaporator system concentrates weak liquor containing \(4 \%\) (by mass) caustic soda to produce a lye containing \(25 \%\) solids (by mass). What is the weight of water evaporated per \(100 \mathrm{~g}\) feed in the evaporator? (a) \(125.0 \mathrm{~g}\) (b) \(50.0 \mathrm{~g}\) (c) \(84.0 \mathrm{~g}\) (d) \(16.0 \mathrm{~g}\)

At \(373 \mathrm{~K}\) and \(1 \mathrm{~atm}\), if the density of liquid water is \(1.0 \mathrm{~g} / \mathrm{ml}\) and that of water vapour is \(0.0006 \mathrm{~g} / \mathrm{ml}\), then the volume occupied by water molecules in 1 litre of steam at that temperature is (a) \(6 \mathrm{ml}\) (b) \(60 \mathrm{ml}\) (c) \(0.6 \mathrm{ml}\) (d) \(0.06 \mathrm{ml}\)

Two isotopes of an element \(\mathrm{Q}\) are \(\mathrm{Q}^{97}\) (23.4\% abundance) and \(Q^{94}\) (76.6\% abundance). \(Q^{97}\) is \(8.082\) times heavier than \(\mathrm{C}^{12}\) and \(\mathrm{Q}^{94}\) is \(7.833\) times heavier than \(\mathrm{C}^{12}\). What is the average atomic weight of the element Q? (a) \(94.702\) (b) \(78.913\) (c) \(96.298\) (d) \(94.695\)

If the atomic mass were given by as \(1 / 6^{\text {th }}\) part and molecular mass as \(1 / 12^{\text {th }}\) part by mass of one atom of \(\mathrm{C}^{12}\) isotope, what would be the molecular mass of water? Suppose Atomic masses of hydrogen and oxygen on new scale are 1 and 16 , respectively, (a) 18 (b) 9 (c) 36 (d) Unpredictable

Two elements \(\mathrm{A}\) and \(\mathrm{B}\) combine to form compound \(X\) and \(Y\). For the fix mass of A, masses of \(\mathrm{B}\) combined for the compounds \(\mathrm{A}\) and \(\mathrm{B}\) are in \(3: 7\) ratio. If in compound \(X, 4 g\) of \(A\) combines with \(12 \mathrm{~g} \mathrm{~B}\), then in compound \(\mathrm{Y}, 8 \mathrm{~g}\) of \(\mathrm{A}\) will combine with \(\ldots \ldots \mathrm{g}\) of \(\mathrm{B}\). (a) 24 (b) 56 (c) 28 (d) 8

The atomic masses of two elements \(\mathrm{P}\) and Q are 20 and 40 , respectively. If ' \(a\) ' \(\mathrm{g}\) of \(\mathrm{P}\) contains ' \(b\) ' atoms, how many atoms are present in ' \(2 a\) ' \(\mathrm{g}\) of \(\mathrm{Q}\) ? (a) \(a\) (b) \(b\) (c) \(2 a\) (d) \(2 b\)

The molecular formula of a compound is \(\mathrm{X}_{4} \mathrm{O}_{9} .\) If the compound contains \(40 \% \mathrm{X}\), by mass, what is the atomic mass of \(X\) ? (a) 24 (b) 12 (c) 26 (d) 13

When a sample of hydrogen fluoride is cooled to \(303 \mathrm{~K}\), most of the molecules undergo dimerization. If the vapour density of such a sample is 18 , what per cent of total molecules in the sample are in dimer form? \((\mathrm{F}=19)\) (a) \(88.89\) (b) \(80.0\) (c) \(20.0\) (d) \(11.11\)

A quantity of \(1 \mathrm{~g}\) of metallic carbonate \(\mathrm{XCO}_{3}\) is completely converted into a \(\begin{array}{lll}\text { chloride } \mathrm{XCl}_{2} \text { weighing } & 1.11 & \text { g. } & \text { The }\end{array}\) atomic mass of the element ' \(\mathrm{X}\) ' is (a) 10 (b) 20 (c) 30 (d) 40

A certain mixture of \(\mathrm{MnO}\) and \(\mathrm{MnO}_{2}\) contains \(66.67\) mol per cent of \(\mathrm{MnO}\). What is the approximate mass per cent of \(\mathrm{Mn}\) in it? \((\mathrm{Mn}=55)\) (a) \(66.67\) (b) \(24.02\) (c) \(72.05\) (d) \(69.62\)

If isotopic distribution of \(\mathrm{C}^{12}\) and \(\mathrm{C}^{14}\) is \(98.0 \%\) and \(2.0 \%\), respectively, then the number of \(\mathrm{C}^{14}\) atoms in \(12 \mathrm{~g}\) of carbon is (a) \(1.032 \times 10^{22}\) (b) \(1.20 \times 10^{22}\) (c) \(5.88 \times 10^{23}\) (d) \(6.02 \times 10^{23}\)

The fractional abundance of \(\mathrm{Cl}^{35}\) in a sample of chlorine containing only \(\mathrm{Cl}^{35}\) (atomic weight \(=34.9\) ) and \(\mathrm{Cl}^{37}\) (atomic weight \(=36.9\) ) isotopes, is \(0.6\). The average mass number of chlorine is (a) \(35.7\) (b) \(35.8\) (c) \(18.8\) (d) \(35.77\)

Twenty molecules of \(\mathrm{SO}_{3}\) will weigh as much as \(\ldots . .\) molecules of oxygen. (a) 100 (b) 50 (c) 15 (d) \(\underline{8}\)

The mass of \(\mathrm{CO}_{2}\) that must be mixed with \(20 \mathrm{~g}\) of oxygen such that \(27 \mathrm{ml}\) of a sample of the resulting mixture would contain equal number of molecules of each gas (a) \(13.75 \mathrm{~g}\) (b) \(27.50 \mathrm{~g}\) (c) \(41.25 \mathrm{~g}\) (d) \(55 \mathrm{~g}\)

The empirical formula of a compound is \(\mathrm{CH}_{2} \mathrm{O}\). If \(0.0833\) moles of the compound contains \(1.0 \mathrm{~g}\) of hydrogen, its molecular formula should be (a) \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) (b) \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}_{5}\) (c) \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{4}\) (d) \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{3}\)

A mixture of \(2 \times 10^{21}\) molecules of \(\mathrm{P}\) and \(3 \times 10^{21}\) molecules of \(\mathrm{Q}\) weighs \(0.60 \mathrm{~g}\). If the molecular mass of \(\mathrm{P}\) is 45, the molecular mass of \(\mathrm{Q}\) will be \(\left(N_{\mathrm{A}}=6 \times 10^{23}\right)\) (a) 45 (b) 180 (c) 90 (d) 270

A hydrocarbon \(\mathrm{C}_{n} \mathrm{H}_{2 n}\) yields \(\mathrm{C}_{n} \mathrm{H}_{2 n+2}\) by reduction. In this process, the molar mass of the compound is raised by \(2.38 \%\). The value of \(n\) is (a) 8 (b) 4 (c) 6 (d) 5

A certain vitamin extracted from plant sources has carbon and hydrogen in \(8: 1\) mass ratio. The percentage of oxygen is nearly 7.3. The compound gave no test for nitrogen or sulphur or any other element. What should be the empirical formula of the compound? (a) \(\mathrm{C}_{30} \mathrm{H}_{45} \mathrm{O}_{2}\) (b) \(\mathrm{C}_{15} \mathrm{H}_{23} \mathrm{O}\) (c) \(\mathrm{C}_{29} \mathrm{H}_{45} \mathrm{O}_{3}\) (d) \(\mathrm{C}_{10} \mathrm{H}_{15} \mathrm{O}\)

The density of a DNA sample is \(1.1 \mathrm{~g} / \mathrm{ml}\) and its molar mass determined by cryoscopic method was found to be \(6 \times 10^{8} \mathrm{~g} / \mathrm{mole}\). What is the volume occupied by one DNA molecule? \(\left(N_{\mathrm{A}}=6 \times 10^{23}\right)\) (a) \(5.45 \times 10^{8} \mathrm{ml}\) (b) \(1.83 \times 10^{-9} \mathrm{ml}\) (c) \(9.06 \times 10^{-16} \mathrm{ml}\) (d) \(1.09 \times 10^{-13} \mathrm{ml}\)

A sample of protein was analysed for metal content and analysis revealed that it contained magnesium and titanium in equal amounts, by mass. If these are the only metallic species present in the protein and it contains \(0.016 \%\) metal, by mass, the minimum possible molar mass of the protein is \((\mathrm{Mg}=24, \mathrm{Ti}=48)\) (a) \(6,00,000\) (b) \(1,50,000\) (c) \(3,00,000\) (d) \(12,00,000\)

Out of \(1.0 \mathrm{~g}\) dioxygen, \(1.0 \mathrm{~g}\) atomic oxygen and \(1.0 \mathrm{~g}\) ozone, the maximum number of oxygen atoms are contained in (a) \(1.0 \mathrm{~g}\) of atomic oxygen (b) \(1.0 \mathrm{~g}\) of ozone (c) \(1.0 \mathrm{~g}\) of oxygen gas (d) All contain the same number of atoms

Total number of electrons present in \(4.4 \mathrm{~g}\) oxalate ion \(\left(\mathrm{C}_{2} \mathrm{O}_{4}^{2-}\right)\) is (a) \(0.05 N_{\mathrm{A}}\) (b) \(2.3 N_{\mathrm{A}}\) (c) \(2.2 N_{\mathrm{A}}\) (d) \(2.1 N_{\mathrm{A}}\)

A quantity of \(13.5 \mathrm{~g}\) of aluminium when changes to \(\mathrm{Al}^{3+}\) ion in solution, will lose \((\mathrm{Al}=27)\) (a) \(18.0 \times 10^{23}\) electrons (b) \(6.02 \times 10^{23}\) electrons (c) \(3.01 \times 10^{23}\) electrons (d) \(9.1 \times 10^{23}\) electrons

When a hydrocarbon is burnt completely, the ratio of masses of \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) formed is \(44: 27\). The hydrocarbon is (a) \(\mathrm{CH}_{4}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{6}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{2}\)

If an iodized salt contains \(1 \%\) of \(\mathrm{KI}\) and a person takes \(2 \mathrm{~g}\) of the salt every day, the iodine ions going into his body everyday would be approximately \((\mathrm{K}=39\), \(\mathrm{I}=127\) ) (a) \(7.2 \times 10^{21}\) (b) \(7.2 \times 10^{18}\) (c) \(3.6 \times 10^{21}\) (d) \(9.5 \times 10^{18}\)

Ethanol is the substance commonly called alcohol. The density of liquid alcohol is \(0.8 \mathrm{~g} / \mathrm{ml}\) at \(293 \mathrm{~K}\). If \(1.2\) moles of ethanol is needed for a particular experiment, what volume of ethanol should be measured out? (a) \(55.2 \mathrm{ml}\) (b) \(57.5 \mathrm{ml}\) (c) \(69 \mathrm{ml}\) (d) \(47.9 \mathrm{ml}\)

A metal oxide has the formula \(\mathrm{M}, \mathrm{O}_{2}\). It can be reduced by hydrogen to give free metal and water. \(0.1596 \mathrm{~g}\) of the metal oxide required \(6 \mathrm{mg}\) of hydrogen for complete reduction. The atomic mass of the metal is (a) \(111.60\) (b) \(159.60\) (c) \(79.80\) (d) \(55.80\)

The volume of one mole of water at \(277 \mathrm{~K}\) is \(18 \mathrm{ml}\). One \(\mathrm{ml}\) of water contains 20 drops. The number of molecules in one drop of water will be \(\left(N_{\mathrm{A}}=6 \times 10^{23}\right)\) (a) \(1.07 \times 10^{21}\) (b) \(1.67 \times 10^{21}\) (c) \(2.67 \times 10^{21}\) (d) \(1.67 \times 10^{20}\)

If \(0.250 \mathrm{~g}\) of an element, \(\mathrm{M}\), reacts with excess fluorine to produce \(0.547 \mathrm{~g}\) of the hexafluoride, \(\mathrm{MF}_{6}\), the element should be \((\mathrm{Cr}=52, \mathrm{Mo}=95.94, \mathrm{~S}=32, \mathrm{Te}=127.6\) \(\mathrm{F}=19\) ) (a) \(\mathrm{Cr}\) (b) Mo (c) \(S\) (d) Te

A given mixture consists only of pure substance \(X\) and pure substance \(Y\). The total mass of the mixture is \(3.72 \mathrm{~g}\). The total number of moles is \(0.06\). If the mass of one mole of \(Y\) is \(48 \mathrm{~g}\) and there is \(0.02\) mole of \(X\) in the mixture, what is the mass of one mole of \(\mathrm{X}\) ? (a) \(90 \mathrm{~g}\) (b) \(75 \mathrm{~g}\) (c) \(45 \mathrm{~g}\) (d) \(180 \mathrm{~g}\)

Fluorine reacts with uranium hexafluoride, \(\mathrm{UF}_{6}\), as represented by this equation: \(\mathrm{U}(\mathrm{s})+3 \mathrm{~F}_{2}(\mathrm{~g}) \rightarrow \mathrm{UF}_{6}(\mathrm{~g})\) How many fluorine molecules are required to produce \(2.0 \mathrm{mg}\) of uranium hexafluoride, \(\mathrm{UF}_{6}\), from an excess of uranium? The molar mass of \(\mathrm{UF}_{6}\) is \(352.0 \mathrm{~g} \mathrm{~mol}^{-1} .\) (a) \(5.13 \times 10^{18}\) (b) \(1.026 \times 10^{19}\) (c) \(2.052 \times 10^{19}\) (d) \(1.026 \times 10^{20}\)

Number of gas molecules present in \(1 \mathrm{ml}\) of gas at \(0{ }^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\) is called Loschmidt number. Its value is about (a) \(2.7 \times 10^{19}\) (b) \(6 \times 10^{23}\) (c) \(2.7 \times 10^{22}\) (d) \(1.3 \times 10^{28}\)

What is the total mass of the products formed, when \(51 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{~S}\) is oxidized by oxygen to produce water and sulphur dioxide? (a) \(72 \mathrm{~g}\) (b) \(27 \mathrm{~g}\) (c) \(123 \mathrm{~g}\) (d) \(96 \mathrm{~g}\)

A quantity of \(0.25 \mathrm{~g}\) of a substance when vaporized displaced \(50 \mathrm{~cm}^{3}\) of air at \(0^{\circ} \mathrm{C}\) and 1 atm. The gram molecular mass of the substance will be (a) \(50 \mathrm{~g}\) (b) \(100 \mathrm{~g}\) (c) \(112 \mathrm{~g}\) (d) \(127.5 \mathrm{~g}\)

A compound of iron and chlorine is soluble in water. An excess of silver nitrate was added to precipitate all chloride ions as silver chloride. If a \(127 \mathrm{mg}\) sample of the compound gave \(287 \mathrm{mg} \mathrm{AgCl}\), what is the formula of the compound? \((\mathrm{Fe}=56\), \(\mathrm{Ag}=108\) ) (a) \(\mathrm{FeCl}_{2}\) (b) \(\mathrm{FeCl}_{3}\) (c) \(\mathrm{FeCl}\) (d) \(\mathrm{FeCl}_{6}\)

A quantity of \(2.0 \mathrm{~g}\) of a triatomic gaseous element was found to occupy a volume of \(448 \mathrm{ml}\) at \(76 \mathrm{~cm}\) of \(\mathrm{Hg}\) and \(273 \mathrm{~K}\). The mass of its each atom is (a) 100 amu (b) \(5.53 \times 10^{-23} \mathrm{~g}\) (c) \(33.3 \mathrm{~g}\) (d) \(5.53\) amu

Most abundant element dissolved in sea water is chlorine at a concentration of \(19 \mathrm{~g} / \mathrm{kg}\) of sea water. The volume of earth's ocean is \(1.4 \times 10^{21} 1\). How many g-atoms of chlorine are potentially available from the oceans? Density of sea water is \(1 \mathrm{~g} / \mathrm{ml} .\left(N_{\mathrm{A}}=6 \times 10^{23}\right)\) (a) \(7.5 \times 10^{20}\) (b) \(27 \times 10^{2}\) (c) \(27 \times 10^{24}\) (d) \(7.5 \times 10^{19}\)

From \(2 \mathrm{mg}\) calcium, \(1.2 \times 10^{19}\) atoms are removed. The number of g-atoms of calcium left is \((\mathrm{Ca}=40)\) (a) \(5 \times 10^{-5}\) (b) \(2 \times 10^{-5}\) (c) \(3 \times 10^{-5}\) (d) \(5 \times 10^{-6}\)

A \(1.50 \mathrm{~g}\) sample of type metal (an alloy of \(\mathrm{Sn}, \mathrm{Pb}, \mathrm{Cu}\) and \(\mathrm{Sb}\) ) is dissolved in nitric acid, and metastannic acid, \(\mathrm{H}_{2} \mathrm{SnO}_{3}\), precipitates. This is dehydrated by heating to tin (IV) oxide, which is found to weigh \(0.50 \mathrm{~g}\). What percentage of tin was in the original type metal sample? \((\mathrm{Sn}=119)\) (a) \(33.33 \%\) (b) \(26.27 \%\) (c) \(29.38 \%\) (d) \(52.54 \%\)

Equal masses of oxygen, hydrogen and methane are taken in identical conditions. What is the ratio of the volumes of the gases under identical conditions? (a) \(16: 1: 8\) (b) \(1: 16: 2\) (c) \(1: 16: 8\) (d) \(2: 16: 1\)

Hydrogen cyanide, \(\mathrm{HCN}\), can be made by a two-step process. First, ammonia is reacted with \(\mathrm{O}_{2}\) to give nitric oxide, \(\mathrm{NO}\). \(4 \mathrm{NH}_{3}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})\) Then nitric oxide is reacted with methane, \(\mathrm{CH}_{4}\) \(2 \mathrm{NO}(\mathrm{g})+2 \mathrm{CH}_{4}(\mathrm{~g}) \rightarrow 2 \mathrm{HCN}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})\) \(+\mathrm{H}_{2}(\mathrm{~g})\) When \(25.5 \mathrm{~g}\) of ammonia and \(32.0 \mathrm{~g}\) of methane are used, how many grams of hydrogen cyanide can be produced? (a) \(1.5\) (b) \(2.0\) (c) \(40.5\) (d) \(54.0\)

A pre-weighed vessel was filled with oxygen at NTP and weighed. It was then evacuated, filled with \(\mathrm{SO}_{2}\) at the same temperature and pressure, and again weighed. The weight of oxygen is (a) the same as that of \(\mathrm{SO}_{2}\) (b) \(\frac{1}{2}\) that of \(\mathrm{SO}_{2}\) (c) twice that of \(\mathrm{SO}_{2}\) (d) \(\frac{1}{4}\) that of \(\mathrm{SO}_{2}\)

To determine soluble (free) \(\mathrm{SiO}_{2}\) in a rock. an alkaline extraction was carried out, as a result of which there was found \(1.52 \%\) of \(\mathrm{SiO}_{2}\) in the extract and also \(1.02 \%\) of \(\mathrm{Al}_{2} \mathrm{O}_{3} .\) Considering that, apart from the free \(\mathrm{SiO}_{2}\), the extract also contained the \(\mathrm{SiO}_{2}\) that had passed into it from Kaolin \(\left(2 \mathrm{SiO}_{2} \cdot \mathrm{Al}_{2} \mathrm{O}_{3}\right)\), the percentage of free \(\mathrm{SiO}_{2}\) in the rock being analysed is \((\mathrm{Si}=28\), \(\mathrm{Al}=27\) ) (a) \(1.20\) (b) \(0.32\) (c) \(0.50\) (d) \(1.52\)