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JEE • CHEMISTRY • SOME BASIC CONCEPTS OF CHEMISTRY

Some basic concepts of chemistry practice · Hard

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1 Hard
1 of 77
Application +4 | -1
8 g of NaOH is dissolved in 18 g of H2O.{H_2}O. Mole fraction of NaOH in solution and molality (in mol  kg−1)mol\,\,k{g^{ - 1}}) of the solution respectively are
View answer and explanation
Correct option: D
0.167, 11.11
Option D (0.167, 11.11) is correct because it accurately calculates the mole fraction of NaOH and the molality of the solution.
2 Hard
2 of 77
Application +4 | -1
A sample of sodium has a mass of 46 g46 \mathrm{~g}. What is the mass of the same number of calcium atoms as sodium atoms present in given sample?
View answer and explanation
Correct option: D
80 g80 \mathrm{~g}
Option D (80 g80 \mathrm{~g}) is correct because the mass of the same number of calcium atoms is twice the mass of sodium atoms since the atomic mass of calcium is approximately twice that of sodium.
3 Hard
3 of 77
Application +4 | -1
The most abundant elements by mass in the body of a healthy human adult are Oxygen (61.4%); Carbon (22.9%), Hydrogen (10.0%); and Nitrogen (2.6%). The weight which a 75 kg person would gain if all 1H{}^1H atoms are replaced by 2H{}^2H atoms is
View answer and explanation
Correct option: C
7.5 kg
Option C (7.5 kg) is correct because it is the mass gain calculated by replacing all 1H{}^1H atoms with 2H{}^2H atoms.
4 Hard
4 of 77
Application +4 | -1
50 mL50 \mathrm{~mL} of 0.01 M FeSO40.01 \mathrm{~M} \mathrm{~FeSO}_4 will react with what volume of 0.01 M KMnO40.01 \mathrm{~M} \mathrm{~KMnO}_4 solution in acid medium? (1 mol KMnO4\left(1 \mathrm{~mol} \mathrm{~KMnO}_4\right. requires 5 mol5 \mathrm{~mol} of FeSO4\mathrm{FeSO}_4 for complete reaction)
View answer and explanation
Correct option: D
10 mL10 \mathrm{~mL}
Option D (10 mL10 \mathrm{~mL}) is correct because the volume of KMnO4 required is calculated using the stoichiometry of the reaction.
5 Hard
5 of 77
Application +4 | -1
If 6.256.25 is to be rounded off to AA and if 6.356.35 is to be rounded off to BB. Here, AA and BB refer to
View answer and explanation
Correct option: A
A→6.2,B→6.4A \rightarrow 6.2, B \rightarrow 6.4
Option A (A→6.2,B→6.4A \rightarrow 6.2, B \rightarrow 6.4) is correct because it follows the rounding rules where if the rightmost digit to be removed is 5, the preceding even number remains unchanged, and the preceding odd number is increased by one.
6 Hard
6 of 77
Application +4 | -1
Density of dry air containing only N2\mathrm{N}_2 and O2\mathrm{O}_2 is 1.15 g/L1.15 \mathrm{~g} / \mathrm{L} at 740 mm740 \mathrm{~mm} of Hg\mathrm{Hg} and 300 K300 \mathrm{~K}. What is %\% composition of N2\mathrm{N}_2 by weight in the air?
View answer and explanation
Correct option: C
70.02%70.02 \%
Option C (70.02%70.02 \%) is correct because it is calculated using the ideal gas law and weighted average molar mass to find the percentage composition of N2 by weight.
7 Hard
7 of 77
Application +4 | -1
2.4 kg of carbon is made to react with 1.35 kg of aluminium to form Al4C3.Al_4C_3. The maximum amount (in kg) of aluminium carbide formed is
View answer and explanation
Correct option: D
1.8
The correct answer is 1.8 kg because Aluminium is the limiting reagent. The maximum amount of aluminium carbide formed is determined by the limiting reactant.
8 Hard
8 of 77
Application +4 | -1
The amount of BaSO4{BaSO}_4 formed upon mixing 100 mL100 {~mL} of 20.8% BaCl220.8 \% \,{BaCl}_2 solution with 50 mL50 {~mL} of 9.8%H2SO49.8 \% {H}_2 {SO}_4 solution with 50 mL50 {~mL} of 9.8% 9.8 \%\, H2SO4{H}_2 {SO}_4 solution will be:

(Ba=137,Cl=35.5, S=32,H=1 and O=16 ) ({Ba}=137, {Cl}=35.5, {~S}=32, {H}=1 \text { and } {O}=16 \text { ) }
View answer and explanation
Correct option: A
23.3 g23.3 {~g}
Option A (23.3 g23.3 {~g}) is correct because it is the mass of BaSO4{BaSO}_4 formed based on the stoichiometry of the reaction between BaCl2{BaCl}_2 and H2SO4{H}_2 {SO}_4.
9 Hard
9 of 77
Analyzing +4 | -1
Assertion:- 44 g44 \mathrm{~g} of CO2,28 g\mathrm{CO}_2, 28 \mathrm{~g} of CO\mathrm{CO} have same volume at STP.

Reason:- Both CO2\mathrm{CO}_2 and CO\mathrm{CO} are formed by C\mathrm{C} and oxygen.
View answer and explanation
Correct option: B
If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion
Option B is correct. The assertion is true because equal moles of gases occupy the same volume at STP. The reason is also true but doesn't explain the assertion.
10 Hard
10 of 77
Application +4 | -1
Calculate the molality of 1 litre solution of 93% H2SO493 \% \, \mathrm{H}_2 \mathrm{SO}_4 (weight/volume). The density of the solution is 1.84 g/mL1.84 \mathrm{~g} / \mathrm{mL}.
View answer and explanation
Correct option: C
10.42 m
Option C (10.42 m) is correct because the molality is calculated using the mass of solute and solvent in the solution.
11 Hard
11 of 77
Application +4 | -1
Complete combustion of 0.858 g0.858 \mathrm{~g} of compound XX gives 2.64 g2.64 \mathrm{~g} of CO2\mathrm{CO}_2 and 1.26 gof H2O1.26 \mathrm{~g}_{\text {of }} \mathrm{H}_2 \mathrm{O}. The lowest molecular mass XX can have :
View answer and explanation
Correct option: A
43 g43 \mathrm{~g}
Option B (21) is correct because it is the equivalent weight calculated based on the change in oxidation state of iron.
12 Hard
12 of 77
Application +4 | -1
A 4 g4 \mathrm{~g} mixture of Na2O\mathrm{Na}_2 \mathrm{O} and NaCl\mathrm{NaCl} was dissolved in 400 mL400 \mathrm{~mL} of 0.3 M HCl0.3 \mathrm{~M} \mathrm{~HCl}. After complete reaction, the resulting solution required 200 mL200 \mathrm{~mL} of 0.2 M NaOH0.2 \mathrm{~M} \mathrm{~NaOH} for complete neutralization of the excess HCl\mathrm{HCl}. What mass %\% of Na2O\mathrm{Na}_2 \mathrm{O} is present in the mixture?
View answer and explanation
Correct option: C
62%62 \%
Option C (62%) is correct because it is calculated by finding the moles of Na2O that reacted with HCl and then calculating the mass percent.
13 Hard
13 of 77
Application +4 | -1
A spherical ball of radius 7 cm7 \mathrm{~cm} contains 56%56 \% iron. If density is 1.4 g cm−3,1.4 \mathrm{~g} \mathrm{~cm}^{-3}, number of moles of Fe\text{Fe} present approximately is
View answer and explanation
Correct option: C
20
Option C (20) is correct because it is calculated based on the volume of the sphere, density, percentage of iron, and the molar mass of iron.
14 Hard
14 of 77
Remembering +4 | -1
Which of the following is not described in Charaka Samhita?
View answer and explanation
Correct option: C
Preparation of perfumes and cosmetics
Option C (Preparation of perfumes and cosmetics) is correct because the preparation of perfumes and cosmetics was described in Brihat Samhita, not Charaka Samhita.
15 Hard
15 of 77
Application +4 | -1
A compound used in making nylon, is 43.8%43.8 \% oxygen. There are four oxygen atoms per molecule. What is the molecular weight of compound?
View answer and explanation
Correct option: D
146146
Option D (146146) is correct because it is the molecular weight calculated from the percentage of oxygen and the number of oxygen atoms per molecule.
16 Hard
16 of 77
Understanding +4 | -1
Assertion: Equivalence point is a theoretical value.
Reason: End point is an experimental value.
View answer and explanation
Correct option: D
Both Assertion and Reason are correct but Reason is not correct explanation of Assertion
Option D is correct because both the Assertion and Reason are correct, but the Reason is not the correct explanation of the Assertion. The equivalence point is a theoretical value, and the endpoint is an experimental value, but the endpoint being experimental doesn't explain why the equivalence point is theoretical.
17 Hard
17 of 77
Analyzing +4 | -1
0.1 M solution of KI reacts with excess of H2SO4\mathrm{H}_2 \mathrm{SO}_4 and KIO3\mathrm{KIO}_3 solution. According to equation

5I−+IO3−+6H+→3I2+3H2O5 \mathrm{I}^{-}+\mathrm{IO}_3^{-}+6 \mathrm{H}^{+} \rightarrow 3 \mathrm{I}_2+3 \mathrm{H}_2 \mathrm{O}

Identify the correct statements:

(A) 200 mL of KI solution reacts with 0.004 mol of KIO3\mathrm{KIO}_3

(B) 200 mL of KI solution reacts with 0.006 mol of H2SO4\mathrm{H}_2 \mathrm{SO}_4

(3) 0.5 L of KI solution produced 0.005 mol of I2\mathrm{I}_2

(4) Equivalent weight of KIO3\mathrm{KIO}_3 is equal to (Molecular weight5)\left(\frac{\text {Molecular weight}}{5}\right)

Choose the correct answer from the options given below:
View answer and explanation
Correct option: A
(A) and (D) only
The correct answer is A ((A) and (D) only) because the stoichiometry of the reaction confirms that 200 mL of 0.1 M KI reacts with 0.004 mol of KIO3, and the equivalent weight of KIO3 is Molecular weight/5.
18 Hard
18 of 77
Application +4 | -1
How many millilitres of a 0.05 M KMnO40.05 \mathrm{~M} \mathrm{~KMnO}_4 solution are required to oxide 2.0 g2.0 \mathrm{~g} of FeSO4\mathrm{FeSO}_4 in a dilute acid solution? (Fe=56,S=32,O=16)(\mathrm{Fe}=56, \mathrm{S}=32, \mathrm{O}=16).
View answer and explanation
Correct option: A
53
Option A (53) is correct because the volume of KMnO4 required is calculated using stoichiometry and molarity, resulting in approximately 53 mL.
19 Hard
19 of 77
Application +4 | -1
The density of 3M3 \mathrm{M} solution of NaCl\mathrm{NaCl} is 1.25 g mL−11.25 \mathrm{~g} \mathrm{~mL}^{-1}. Calculate the molality of the solution.
View answer and explanation
Correct option: A
2.79 m
Option A (2.79 m) is correct because molality is calculated by dividing the moles of solute by the mass of the solvent in kg, considering the density of the solution.
20 Hard
20 of 77
Application +4 | -1
5 moles of AB2A{B_2} weight 125×10−3kg125 \times {10^{ - 3}}kg and 10 moles of A2B2{A_2}{B_2} weight 300×10−3kg300 \times {10^{ - 3}}kg. The molar mass of A(MA)A\left( {{M_A}} \right) and molar mass of B(MB)B\left( {{M_B}} \right) in kg mol−1\mathrm{mo}{\mathrm{l}^{ - 1}} are
View answer and explanation
Correct option: D
MA=5×10−3{M_A} = 5 \times {10^{ - 3}} and MB=10×10−3{M_B} = 10 \times {10^{ - 3}}
Option D (MA=5×10−3{M_A} = 5 \times {10^{ - 3}} and MB=10×10−3{M_B} = 10 \times {10^{ - 3}}) is correct because it is the solution to the system of equations derived from the given masses and moles of the compounds AB2AB_2 and A2B2A_2B_2.
21 Hard
21 of 77
Analyzing +4 | -1
Assertion: Sulphate is estimated as BaSO4\mathrm{BaSO}_4 and not as MgSO4\mathrm{MgSO}_4.
Reason: Ionic radius of Mg2+\mathrm{Mg}^{2+} is smaller than Ba2+\mathrm{Ba}^{2+}.
View answer and explanation
Correct option: D
Both Assertion and Reason are correct but Reason is not correct explanation of Assertion
Option D (Both Assertion and Reason are correct but Reason is not correct explanation of Assertion) is correct because while both statements are true, the smaller ionic radius of Mg2+ doesn't directly explain why sulfate is estimated as BaSO4.
22 Hard
22 of 77
Application +4 | -1
Mole fraction of A in water is 0.2. The molality of A in water is:
View answer and explanation
Correct option: A
13.8
Option A (13.8) is correct because it is calculated by converting mole fraction to molality using the molar mass of water.
23 Hard
23 of 77
Application +4 | -1
In the balanced chemical reaction, IO3−+al−+bH+⟶CH2O+dl2\mathrm{IO}_3^{-}+\mathrm{al}^{-}+\mathrm{bH}^{+} \longrightarrow \mathrm{CH}_2 \mathrm{O}+\mathrm{dl}_2. a, b, c and d respectively correspond to
View answer and explanation
Correct option: A
5,6,3,35,6,3,3
Option A (5,6,3,3) is correct because it represents the stoichiometric coefficients that balance the redox reaction.
24 Hard
24 of 77
Application +4 | -1
Suppose that AA and BB form the compounds B2A3B_2 A_3 and B2AB_2 A. If 0.05 mole of B2A3B_2 A_3 weighs 9 g9 \mathrm{~g} and 0.1 mole of B2AB_2 A weighs 10 g10 \mathrm{~g}, the atomic weight of AA and BB respectively are
View answer and explanation
Correct option: B
40 and 30
Option B (40 and 30) is correct because solving the system of equations derived from the molar masses of the compounds yields these atomic weights.
25 Hard
25 of 77
Application +4 | -1
Amount of FeSO4{FeSO}_4 solution required containing 20%(w/w)FeSO420 \%(w / w) {FeSO}_4 for complete titration of 100 ml100 \,{ml} of 0.1  M  KMnO40.1 \,\,{M}\,\, {KMnO}_4 solution in acidic medium is
View answer and explanation
Correct option: B
38  g38 \,{~g}
Option B (110.2) is correct because the change in standard entropy is calculated using the formula ΔG∘=ΔH∘−TΔS∘\Delta G^{\circ}=\Delta H^{\circ}-T \Delta S^{\circ}.
26 Hard
26 of 77
Application +4 | -1
A quantity of 27.6 g27.6 \mathrm{~g} of K2CO3\mathrm{K}_2 \mathrm{CO}_3 was treated by a series of reagent so as to convert all of its carbon to K2Zn3[Fe(CN)6]2.\mathrm{K}_2 \mathrm{Zn}_3\left[\mathrm{Fe}(\mathrm{CN})_6\right]_2. The mass of the product formed is (K=39,Zn=65.4,Fe=56)(\mathrm{K}=39, \mathrm{Zn}=65.4, \mathrm{Fe}=56)
View answer and explanation
Correct option: B
11.6 g11.6 \mathrm{~g}
Option B (11.6 g) is correct because it is calculated based on the stoichiometry of the reaction and the molar masses of the compounds involved.
27 Hard
27 of 77
Application +4 | -1
21.75g of MnO2Mn{O_2} on reaction with HCl forms 2.8 L of Cl2(g)C{l_2}\left( g \right) at STP, the percentage purity of MnO2Mn{O_2} is (atomic mass of Mn = 55u)
MnO2+4HCl→MnCl2+Cl2+2H2OMn{O_2} + 4HCl \to MnC{l_2} + C{l_2} + 2{H_2}O
View answer and explanation
Correct option: D
0.5
Option D (0.5) is correct because the percentage purity is calculated by comparing the actual yield of Cl2Cl_2 to the theoretical yield based on the amount of MnO2MnO_2 used.
28 Hard
28 of 77
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.
29 Hard
29 of 77
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.
30 Hard
30 of 77
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.
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