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JEE • CHEMISTRY • SOME BASIC CONCEPTS OF CHEMISTRY

Some basic concepts of chemistry practice · Mixed difficulty

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181 Medium
181 of 436
Application +4 | -1
If a piece of copper weighs 0.635 g0.635 \mathrm{~g}, how many atoms does it contain?
View answer and explanation
Correct option: A
6.023×10216.023 \times 10^{21}
Option A (6.023×10216.023 \times 10^{21}) is correct because it is calculated by dividing the given mass by the molar mass and multiplying by Avogadro's number.
182 Easy
182 of 436
Application +4 | -1
Four faradays of electricity is passed through a solution of CuSO4{CuSO}_4. The mass of copper deposited at the cathode is: (At. mass of Cu=63.5amu{Cu}=63.5 \mathrm{amu} ).
View answer and explanation
Correct option: C
127 g127 \mathrm{~g}
Option C (127 g127 \mathrm{~g}) is correct because it represents the mass of copper deposited when four faradays of electricity are passed through a CuSO4CuSO_4 solution.
183 Medium
183 of 436
Application +4 | -1
An element (X)(\mathrm{X}) reacts with hydrogen leading to formation of a class of compounds that is analogous to hydrocarbons. 5 g5 \mathrm{~g} of X\mathrm{X} forms 5.628 g5.628 \mathrm{~g} of a mixture of two compounds of X(XH4\mathrm{X}\left(\mathrm{XH}_4\right. and X2H6)\left.\mathrm{X}_2 \mathrm{H}_6\right) in the molar ratio of 2:1.2: 1. Determine the molar mass of X.\mathrm{X}.
View answer and explanation
Correct option: A
28
Option A (28) is correct because applying the Principle of Atomic Conservation (POAC) on element X allows us to determine its molar mass.
184 Medium
184 of 436
Application +4 | -1
Rest mass of 1 mole neutrons (mn=1.675×10−27 kg)\left(m_{\mathrm{n}}=1.675 \times 10^{-27} \mathrm{~kg}\right) is:
View answer and explanation
Correct option: D
1.008×10−3 kg1.008 \times 10^{-3} \mathrm{~kg}
Option D (1.008×10−3 kg1.008 \times 10^{-3} \mathrm{~kg}) is correct because it is the product of the mass of one neutron and Avogadro's number.
185 Medium
185 of 436
Application +4 | -1
Number of moles of hydrogen atoms present in 60 amu60 \mathrm{~amu} of acetic acid:
View answer and explanation
Correct option: A
4/NA4 / \mathrm{N}_{\mathrm{A}}
Option A (4/NA4 / N_A) is correct because one molecule of acetic acid contains 4 hydrogen atoms, and we are dealing with one molecule (60 amu).
186 Easy
186 of 436
Application +4 | -1
Vapour density of a volatile substance is (CH4=1)(\mathrm{C}{\mathrm{H}_4} = \mathrm{ }1\mathrm{ }). Its molecular weight would be:
View answer and explanation
Correct option: C
64
Option C (64) is correct because the molecular weight is twice the vapor density, and the vapor density is given relative to methane (CH4 = 1).
187 Medium
187 of 436
Application +4 | -1
1.00×10−31.00 \times 10^{-3} moles of Ag+{Ag}^{+}and 1.00×10−31.00 \times 10^{-3} moles of CrO42−{CrO}_4^{2-} react together to form solid Ag2CrO4{Ag}_2 {CrO}_4. Calculate the amount of Ag2CrO4{Ag}_2 {CrO}_4 formed (Ag2CrO4=331.73 g mol−1)\left({Ag}_2 {CrO}_4=331.73 \mathrm{~g} \mathrm{~mol}^{-1}\right).
View answer and explanation
Correct option: B
0.166 g0.166 \mathrm{~g}
Option B (0.166 g0.166 \mathrm{~g}) is correct because it is the mass of Ag₂CrO₄ formed, calculated using the limiting reagent concept.
188 Easy
188 of 436
Remembering +4 | -1
Molarity is expressed as:
View answer and explanation
Correct option: B
Mol  litre−1\mathrm{Mol\; litr}{\mathrm{e}^{ - 1}}
Option B (Mol  litre−1\mathrm{Mol\; litr}{\mathrm{e}^{ - 1}}) is correct because molarity is defined as moles of solute per liter of solution.
189 Medium
189 of 436
Application +4 | -1
Number of molecules in 1 litre of oxygen at NTP is:
View answer and explanation
Correct option: B
6.02×102322.4\frac{6.02 \times 10^{23}}{22.4}
Option B is correct because at NTP, 1 mole of any gas occupies 22.4 L, so the number of molecules in 1 L is Avogadro's number divided by 22.4.
190 Medium
190 of 436
Analyzing +4 | -1
100 mL100 \mathrm{~mL} of 10% NaOH(w/V)10 \% \mathrm{~NaOH}(w / \mathrm{V}) is added to 100 mL100 \mathrm{~mL} of 10%HCl(w/V)10 \% \mathrm{HCl}(w / \mathrm{V}). The resultant solution becomes:
View answer and explanation
Correct option: C
acidic
Option C (acidic) is correct. The number of moles of HCl is greater than the number of moles of NaOH, resulting in an acidic solution.
191 Medium
191 of 436
Understanding +4 | -1
Statement I: The molality of the solution does not change with temperature.

Statement II: The molality is expressed in the unit of mol\mathrm{mol} kg−1\mathrm{kg}^{-1} of solvent.
View answer and explanation
Correct option: B
Statement I is true; Statement II is true Statement II is not the correct explanation of Statement I
Option B (Statement I is true; Statement II is true Statement II is not the correct explanation of Statement I) is correct because molality is defined as moles of solute per kg of solvent, which is mass-based and thus independent of temperature, but this definition doesn't explain the temperature independence.
192 Hard
192 of 436
Application +4 | -1
For the reaction: 2A+B→C,82 \mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}, 8 mole of A\mathrm{A} and excess of B\mathrm{B} will produce
View answer and explanation
Correct option: B
4 mole of C
Option B (4 mole of C) is correct because according to the stoichiometry of the reaction, 2 moles of A produce 1 mole of C, so 8 moles of A will produce 4 moles of C.
193 Medium
193 of 436
Application +4 | -1
The number of moles of water present in a spherical water droplet of radius 1.0 cm1.0 \mathrm{~cm} is

[Given: density of water in the droplet =1.0 g=1.0 \mathrm{~g} cm−3]\left.\mathrm{cm}^{-3}\right]
View answer and explanation
Correct option: B
2π27\frac{2 \pi}{27}
Option B (2π/27) is correct because the number of moles of water is calculated from the volume of the sphere, density of water, and molar mass of water.
194 Medium
194 of 436
Analyzing +4 | -1
The equivalent weight of Fe3O4\mathrm{Fe}_3 \mathrm{O}_4 in the reaction, Fe3O4+KMnO4→Fe2O3+MnO2\mathrm{Fe}_3 \mathrm{O}_4+\mathrm{KMnO}_4 \rightarrow \mathrm{Fe}_2 \mathrm{O}_3+\mathrm{MnO}_2 would be
View answer and explanation
Correct option: B
MM
Option B (M) is correct because the n-factor for Fe3O4 in the given reaction is 1, so the equivalent weight is M/1 = M.
195 Medium
195 of 436
Application +4 | -1
Molarity and molality of a solution of an liquid (mol. wt. =50=50 ) in aqueous solution is 9 and 10 respectively. What is the density of solution?
View answer and explanation
Correct option: D
1.35 g/cc1.35 \mathrm{~g} / \mathrm{cc}
Option D (1.35 g/cc) is correct because the density is calculated using the molarity, molality, and molecular weight of the solute.
196 Easy
196 of 436
Application +4 | -1
The number of oxygen atoms in 24.9 g24.9 \mathrm{~g} of CuSO4⋅5H2O\mathrm{CuSO}_4 \cdot 5 \mathrm{H}_2 \mathrm{O} is (molar mass of Cu=63 g mol−1\mathrm{Cu}=63 \mathrm{~g} \mathrm{~mol}^{-1})
View answer and explanation
Correct option: C
5.42×10235.42 \times 10^{23}
The correct answer is 5.42×10235.42 \times 10^{23} because the number of oxygen atoms is calculated from the moles of the compound and the number of oxygen atoms per molecule.
197 Easy
197 of 436
Application +4 | -1
Active mass of 0.64 g SO20.64 \mathrm{~g}\, {SO}_2 in 10 lit vessel is
View answer and explanation
Correct option: B
10−3 M10^{-3}\, \mathrm{M}
Option B (10−310^{-3} M) is correct because the active mass is calculated by dividing the number of moles by the volume in liters.
198 Hard
198 of 436
Application +4 | -1
A 0.50 MM solution of KIKI reacts with excess of H2SO4{\mathrm{H}_2}\mathrm{S}{\mathrm{O}_4} and KIO3\mathrm{KI}{\mathrm{O}_3} solutions according to the equation, 6H++5I−+IO3−→3I2+3H2O6{\mathrm{H}^ + } + 5{\mathrm{I}^ - } + \mathrm{IO}_3^ - \to 3{\mathrm{I}_2} + 3{\mathrm{H}_2}\mathrm{O}. Which of the following statements is true?
View answer and explanation
Correct option: C
0.5 litre of the KIKI solution produces 0.15 mole of I2{\mathrm{I}_2}
Option C (0.5 litre of the KIKI solution produces 0.15 mole of I2{\mathrm{I}_2}) is correct because 5 moles of I−I^- produces 3 moles of I2I_2.
199 Medium
199 of 436
Application +4 | -1
The percentage weight of ZnZn in white vitriol [ZnSO4⋅7H2O]\left[ZnSO_4 \cdot 7H_2O\right] is approximately equal to (Zn=65, S=32, O=16 and H=1)\left(Zn=65, \, S=32, \, O=16 \, \text{and} \, H=1\right)
View answer and explanation
Correct option: D
22.65%22.65 \%
Option D (22.65%22.65 \%) is correct because it is calculated by dividing the mass of Zn by the molecular weight of the compound and multiplying by 100.
200 Medium
200 of 436
Analyzing +4 | -1
Statement I: The number of atoms in a given mass of dioxygen (oxygen) and trioxygen (ozone) gases is same.

Statement II: The number of atoms depends on atomic mass, not on molecular mass.
View answer and explanation
Correct option: A
If both statements are CORRECT, and Statement II is the CORRECT explanation of Statement I
If both statements are CORRECT, and Statement II is the CORRECT explanation of Statement I. Same mass, same element and hence, same number of atoms.
201 Medium
201 of 436
Application +4 | -1
On analysis a certain compound was found to contain iodine and oxygen in the ration 254 g of iodine and 80 g of oxygen. The atomic mass of iodine is 127 and that of oxygen is 16. Which is the formula of the compound?
View answer and explanation
Correct option: D
I2O5{\mathrm{I}_2}{\mathrm{O}_5}
Option D (I2O5{\mathrm{I}_2}{\mathrm{O}_5}) is correct because the ratio of iodine to oxygen atoms is 2:5 after converting masses to moles.
202 Medium
202 of 436
Analyzing +4 | -1
For the reaction: Fe2 S3⟶FeSO4+SO2\mathrm{Fe}_2 \mathrm{~S}_3 \longrightarrow \mathrm{FeSO}_4+\mathrm{SO}_2. The equivalent mass of Fe2 S3\mathrm{Fe}_2 \mathrm{~S}_3 is (M is the mol wt of Fe2 S3\mathrm{Fe}_2 \mathrm{~S}_3 )
View answer and explanation
Correct option: D
M20\frac{M}{20}
Option D (M20\frac{M}{20}) is correct because the n-factor for the given reaction is 20, and the equivalent mass is calculated as M/n.
203 Hard
203 of 436
Analyzing +4 | -1
In the reaction,

2Al(s)+6HCl(aq)→2Al3+(aq)+6Cl−(aq)+3H2(g)2\mathrm{Al}\left( s \right) + 6\mathrm{HCl}\left( {aq} \right) \to 2\mathrm{A}{\mathrm{l}^{3 + }}\left( {aq} \right) + 6\mathrm{C}{\mathrm{l}^ - }\left( {aq} \right) + 3{\mathrm{H}_2}\left( \mathrm{g} \right)
View answer and explanation
Correct option: D
11.2LH2(g)11.2\mathrm{L}{\mathrm{H}_2}\left( \mathrm{g} \right) at STP is produced for every mole HCl(aq) consumed
The correct answer is D because the stoichiometry of the balanced equation shows that 6 moles of HCl produce 3 moles of H2, meaning 1 mole of HCl produces 0.5 moles of H2, which is 11.2 L at STP.
204 Medium
204 of 436
Application +4 | -1
Consider the following reaction

A+4 B+3C+2D⟶5E+3 F{A}+4 {~B}+3 {C}+2 {D} \longrightarrow 5 {E}+3 {~F}

If 4 mole of A,14A, 14 mole of B,6B, 6 mole of CC reacts with 6 mole of DD, then the limiting reagent is
View answer and explanation
Correct option: C
C{C}
Option C (C) is correct because C is the limiting reagent as it is completely consumed before the other reactants.
205 Medium
205 of 436
Analyzing +4 | -1
In the following

NO3−+As2 S3+H2O→AsO43−+NO+SO42−+H+\mathrm{NO}_3^{-}+\mathrm{As}_2 \mathrm{~S}_3+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{AsO}_4^{3-}+\mathrm{NO}+\mathrm{SO}_4^{2-}+\mathrm{H}^{+}

Equivalent weight of As2S3A s_2 S_3 (Molecular weight M) is
View answer and explanation
Correct option: D
M28\frac{M}{28}
Option D (M28\frac{M}{28}) is correct because the equivalent weight is the molecular weight divided by the total number of electrons transferred in the redox reaction.
206 Medium
206 of 436
Application +4 | -1
2 mole of ethyl alcohol are present with 6 mole of water. The mole fraction of alcohol is:
View answer and explanation
Correct option: D
0.25
Option D (0.25) is correct because the mole fraction is calculated by dividing the moles of alcohol by the total moles of the solution.
207 Medium
207 of 436
Application +4 | -1
If the density of water is 1 g cm3\mathrm{c}{\mathrm{m}^3}) then the volume occupied by one molecule of water is approximately
View answer and explanation
Correct option: D
3.0×10−23  cm33.0 \times {10^{ - 23}}\;\mathrm{c}{\mathrm{m}^3}
Option D (3.0×10−23  cm33.0 \times {10^{ - 23}}\;\mathrm{c}{\mathrm{m}^3}) is correct because it is the approximate volume calculated by dividing the molar volume by Avogadro's number.
208 Medium
208 of 436
Application +4 | -1
0.1 mole of a carbohydrate with empirical formula CH2O\mathrm{C}{\mathrm{H}_2}\mathrm{O} contains 1 g of hydrogen. What is its molecular formula?
View answer and explanation
Correct option: A
C5H10O5{\mathrm{C}_5}{\mathrm{H}_{10}}{\mathrm{O}_5}
Option A (C5H10O5{\mathrm{C}_5}{\mathrm{H}_{10}}{\mathrm{O}_5}) is correct because the molecular formula is determined by finding the number of moles of hydrogen and relating it to the empirical formula.
209 Hard
209 of 436
Analyzing +4 | -1
One mole of mixture of N2,NO2\mathrm{N}_2, \mathrm{NO}_2 and N2O4\mathrm{N}_2 \mathrm{O}_4 has a mean molar mass of 55.4 g.55.4 \mathrm{~g}. On heating to a temperature, at which all the N2O4\mathrm{N}_2 \mathrm{O}_4 is dissociated into NO2,\mathrm{NO}_2, the mean molar mass tends to a lower value of 39.6 g.39.6 \mathrm{~g}. What is the mole ratio of N2,NO2\mathrm{N}_2, \mathrm{NO}_2 and N2O4\mathrm{N}_2 \mathrm{O}_4 in the original mixture?
View answer and explanation
Correct option: A
5:1:45: 1: 4
Option A (5: 1: 4) is correct because solving the system of equations derived from the given molar mass data yields the mole ratio of N2, NO2, and N2O4 as 5:1:4.
210 Hard
210 of 436
Application +4 | -1
What will be the minimum molar mass of a compound containing 0.39%0.39 \% of nickel?
View answer and explanation
Correct option: B
15 kg
Option B (15 kg) is correct because it is calculated by assuming the compound contains at least one nickel atom and then determining the molar mass based on the given percentage.
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