Core Syllabus Module

Basic Concepts in Chemistry

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Molecular Mass, Mole Concept and Concentration

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Chapter Elite-20 Challenge Zone

Target Advanced

JEE Advanced 2021

LEVELJEE Advanced

The mole fraction of a solute in a solution is 0.1. At 298 K, molarity of this solution is the same as its molality. Density of this solution at 298 K is 2.0 g cm $^{- 3}$ . The ratio of the molecular weights of the solute and solvent, $(\frac{M W _{solute}}{M W _{solvent}})$ , is

JEE Advanced 2022

LEVELJEE Advanced

The treatment of an aqueous solution of 3.74 g of $Cu(NO_{3})_{2}$ with excess KI results in a brown solution along with the formation of a precipitate. Passing $H_{2} S$ through this brown solution gives another precipitate X. The amount of X (in g) is ______. [Given : Atomic mass of H = 1, N = 14, O = 16, S = 32, K = 39, Cu = 63, I = 127]

JEE Advanced 2022

LEVELJEE Advanced

To check the principle of multiple proportions, a series of pure binary compounds ( $P_{m} Q_{n}$ ) were analyzed and their composition is tabulated below. The correct option(s) is(are) \begin{array}{|c|c|c|} \hline \text{Compound} & \text{Weight \% of P} & \text{Weight \% of Q} \\ \hline 1 & 50 & 50 \\ \hline 2 & 44.4 & 55.6 \\ \hline 3 & 40 & 60 \\ \hline \end{array}

* Multiple Correct Options

(A)

If empirical formula of compound 3 is

P_{3} Q_{4}

, then the empirical formula of compound 2 is

P_{3} Q_{5}

(B)

If empirical formula of compound 3 is

P_{3} Q_{2}

and atomic weight of element P is 20, then the atomic weight of Q is 45.

(C)

If empirical formula of compound 2 is PQ, then the empirical formula of the compound 1 is

P_{5} Q_{4}

(D)

If atomic weight of P and Q are 70 and 35, respectively, then the empirical formula of compound 1 is

P_{2} Q

JEE Advanced 2018

LEVELJEE Advanced

The ammonia prepared by treating ammonium sulphate with calcium hydroxide is completely used by NiCl2.6H2O to form a stable coordination compound. Assume that both the reactions are 100% complete. If 1584 g of ammonium sulphate and 952g of NiCl2.6H2O are used in the preparation, the combined weight (in grams) of gypsum and the nickel-ammonia coordination compound thus produced is______. (Atomic weights in g mol–1: H = 1, N = 14, O = 16, S = 32, Cl = 35.5, Ca = 40, Ni = 59)

JEE Advanced 2022

LEVELJEE Advanced

Dissolving 1.24 g of white phosphorous in boiling NaOH solution in an inert atmosphere gives a gas Q. The amount of CuSO4 (in g) required to completely consume the gas Q is ______. [Given : Atomic mass of H = 1, O = 16, Na = 23, P = 31, S = 32, Cu = 63]

JEE Advanced 2019

LEVELJEE Advanced

The mole fraction of urea in an aqueous urea solution containing 900 g of water is 0.05. If the density of the solution is $1.2 g cm^{- 3}$ , the molarity of urea solution is ___ (Given data : Molar masses of urea and water are $60 g mol^{- 1}$ and $18 g mol^{- 1}$ , respectively)

JEE Main 2020

LEVELJEE Advanced

A $20.0 mL$ solution containing $0.2 g$ impure $H_{2} O_{2}$ reacts completely with $0.316 g$ of $KMnO_{4}$ in acid solution. The purity of $H_{2} O_{2}$ (in $%$ ) is ............. (molecular weight of $H_{2} O_{2} = 34$ ; molecular weight of $KMnO_{4} = 158$ ).

JEE Main 2021

LEVELJEE Advanced

0.4 g mixture of NaOH, $Na_{2} CO_{3}$ and some inert impurities was first titrated with $\frac{N}{10}$ HCl using phenolphthalein as an indicator, 17.5 mL of HCl was required at the end point. After this methyl orange was added and titrated. 1.5 mL of same HCl was required for the next end point. The weight percentage of $Na_{2} CO_{3}$ in the mixture is ............. (Rounded off to the nearest integer).

JEE Main 2020

LEVELJEE Advanced

The volume (in $mL$ ) of $0.125 M$ $AgNO_{3}$ required to quantitatively precipitate chloride ions in $0.3 g$ of $[Co (NH_{3})_{6}] Cl_{3}$ is ......... . $M_{[Co (NH_{3})_{6}] Cl_{3}} = 267.46 g/mol$ $M_{AgNO_{3}} = 169.87 g/mol$

JEE Main 2020

LEVELJEE Advanced

A solution of two components containing $n_{1}$ moles of the 1st component and $n_{2}$ moles of the 2nd component is prepared. $M_{1}$ and $M_{2}$ are the molecular weights of component 1 and 2 respectively. If $d$ is the density of the solution in $g mL^{- 1}$ , $C_{2}$ is the molarity and $χ_{2}$ is the mole-fraction of the 2nd component, then $C_{2}$ can be expressed as

(A)

C_{2} = \frac{1000 χ _{2}}{M _{1} + χ _{2} ( M _{2} - M _{1} )}

(B)

C_{2} = \frac{d χ _{2}}{M _{2} + χ _{2} ( M _{2} - M _{1} )}

(C)

C_{2} = \frac{1000 d χ _{2}}{M _{1} + χ _{2} ( M _{2} - M _{1} )}

(D)

C_{2} = \frac{d χ _{1}}{M _{2} + χ _{2} ( M _{2} - M _{1} )}

JEE Main 2019

LEVELJEE Advanced

A $10 mg$ effervescent tablet containing sodium bicarbonate and oxalic acid releases $0.25 mL$ of $CO_{2}$ at $T = 298.15 K$ and $p = 1 bar$ . If molar volume of $CO_{2}$ is $25.0 L$ under such condition, what is the percentage of sodium bicarbonate in each tablet? [Molar mass of $NaHCO_{3} = 84 g mol^{- 1}$ ]

A chloro compound A, (i) Forms aldehydes on ozonolysis followed by the hydrolysis. (ii) When vaporised completely, 1.53 g of A gives 448 mL of vapour at STP. The number of carbon atoms in a molecule of compound A is ……… .

JEE Main 2021

LEVELJEE Advanced

100 g of propane is completely reacted with 1000 g of oxygen. The mole fraction of carbon dioxide in the resulting mixture is $x \times 1 0^{- 2}$ . The value of $x$ is ........ . (Nearest integer) [Atomic weight : H = 1.008, C = 12.00, O = 16.00]

JEE Main 2016

LEVELJEE Advanced

At $300 K$ and $1 atm$ , $15 mL$ of a gaseous hydrocarbon requires $375 mL$ air containing $20% O_{2}$ by volume for complete combustion. After combustion, the gases occupy $330 mL$ . Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is

(A)

C_{3} H_{8}

(B)

C_{4} H_{8}

(C)

C_{4} H_{10}

(D)

C_{3} H_{6}

JEE Main 2020

LEVELJEE Advanced

The ratio of the mass percentages of 'C' and 'H' and 'C' and 'O' of a saturated acyclic organic compound 'X' are $4 : 1$ and $3 : 4$ respectively. Then, the moles of oxygen gas required for complete combustion of two moles of organic compound 'X' is ......... .

JEE Main 2019

LEVELJEE Advanced

A mixture of 100 mmol of $Ca(OH)_{2}$ and 2 g of sodium sulphate was dissolved in water and the volume was made upto 100 mL. The mass of calcium sulphate formed and the concentration of $OH^{-}$ in resulting solution, respectively, are : (Molar mass of $Ca(OH)_{2}$ , $Na_{2} SO_{4}$ and $CaSO_{4}$ are 74, 143 and $136 g mol^{- 1}$ , respectively; $K_{s p}$ of $Ca(OH)_{2}$ is $5.5 \times 1 0^{- 6}$ )

(A)

13.6 g, 0.28 mol L^{- 1}

(B)

1.9 g, 0.28 mol L^{- 1}

(C)

13.6 g, 0.14 mol L^{- 1}

(D)

1.9 g, 0.14 mol L^{- 1}

JEE Main 2020

LEVELJEE Advanced

The volume, in mL, of $0.02 M K_{2} C r_{2} O_{7}$ solution required to react with $0.288 g$ of ferrous oxalate in acidic medium is …… . (Molar mass of $Fe = 56 g mol^{- 1}$ )

JEE Main 2018

LEVELJEE Advanced

The ratio of mass per cent of C and H of an organic compound ( $C_{x} H_{y} O_{z}$ ) is $6 : 1$ . If one molecule of the above compound ( $C_{x} H_{y} O_{z}$ ) contains half as much oxygen as required to burn one molecule of compound $C_{x} H_{y}$ completely to $C O_{2}$ and $H_{2} O$ . The empirical formula of compound $C_{x} H_{y} O_{z}$ is

(A)

C_{3} H_{6} O_{3}

(B)

C_{2} H_{4} O

(C)

C_{3} H_{4} O_{2}

(D)

C_{2} H_{4} O_{3}

JEE Advanced 2018

LEVELJEE Main

To measure the quantity of $MnCl_{2}$ dissolved in an aqueous solution, it was completely converted to $KMnO_{4}$ using the reaction, $MnCl_{2} + K_{2} S_{2} O_{8} + H_{2} O \to KMnO_{4} + H_{2} SO_{4} + HCl$ (equation not balanced). Few drops of concentrated $HCl$ were added to this solution and gently warmed. Further, oxalic acid ( $225 mg$ ) was added in portions till the colour of the permanganate ion disappeared. The quantity of $MnCl_{2}$ (in $mg$ ) present in the initial solution is ______. (Atomic weights in $g mol^{- 1}$ : $Mn = 55$ , $Cl = 35.5$ )

Micro-Topic Strategy Matrix

Molecular Mass, Mole Concept and Concentration

Stoichiometric and Volumetric Calculations

Chapter Elite-20 Challenge Zone

Comprehension Passage

The value of x is ______.

The value of y is ______.

Dissolving 1.24 g of white phosphorous in boiling NaOH solution in an inert atmosphere gives a gas Q. The amount of CuSO4 (in g) required to completely consume the gas Q is ______. [Given : Atomic mass of H = 1, O = 16, Na = 23, P = 31, S = 32, Cu = 63]

A chloro compound A, (i) Forms aldehydes on ozonolysis followed by the hydrolysis. (ii) When vaporised completely, 1.53 g of A gives 448 mL of vapour at STP. The number of carbon atoms in a molecule of compound A is ……… .

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } The volume, in mL, of 0.02 M K2​Cr2​O7​ solution required to react with 0.288 g of ferrous oxalate in acidic medium is …… . (Molar mass of Fe=56 g mol−1)

The volume, in mL, of $0.02 M K_{2} C r_{2} O_{7}$ solution required to react with $0.288 g$ of ferrous oxalate in acidic medium is …… . (Molar mass of $Fe = 56 g mol^{- 1}$ )