JEE Main > Some Basic Concepts of Chemistry

Explore popular questions from Some Basic Concepts of Chemistry for JEE Main. This collection covers Some Basic Concepts of Chemistry previous year JEE Main questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

In a compound {tex} \mathrm { C } , \mathrm { H } {/tex} and {tex} \mathrm { N } {/tex} atoms are present in {tex} 9 : 1 : 3.5 {/tex} by weight. Molecular weight of compound is {tex} 108 . {/tex} Molecular formula of compound is

A

{tex} \mathrm { C } _ { 2 } \mathrm { H } _ { 6 } \mathrm { N } _ { 2 } {/tex}

B

{tex} \mathrm { C } _ { 3 } \mathrm { H } _ { 4 } \mathrm { N } {/tex}

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 8 } \mathrm { N } _ { 2 } {/tex}

D

{tex} \mathrm { C } _ { 9 } \mathrm { H } _ { 12 } \mathrm { N } _ { 3 } {/tex}

Explanation

Q 2.    

Correct4

Incorrect-1

With increase of temperature, which of these changes?

A

molality

B

weight fraction of solute

molarity

D

mole fraction.

Explanation

Q 3.    

Correct4

Incorrect-1

Number of atoms in {tex}\mathrm 558.5 {/tex} gram {tex} \mathrm { Fe } {/tex} (at. wt. of {tex} \mathrm { Fe } = 55.85 \mathrm { g } {/tex} {tex} \left. \mathrm { mol } ^ { - 1 } \right) {/tex} is

twice that in 60 g carbon

B

{tex} 6.023 \times 10 ^ { 22 } {/tex}

C

half that in {tex}\mathrm{8 \,g \,He} {/tex}

D

{tex} 558.5 \times 6.023 \times 10 ^ { 23 } {/tex}

Explanation

Q 4.    

Correct4

Incorrect-1

What volume of hydrogen gas, at {tex} \mathrm {273 K } {/tex} and {tex} 1\, \mathrm { atm } . {/tex} pressure will be consumed in obtaining {tex} \mathrm {21.6 g } {/tex} of elemental boron {tex} \text { (atomic mass } = 10.8 ) {/tex} from the reduction of boron trichloride by hydrogen?

{tex}67.2 \ L {/tex}

B

{tex}44.8 \ \mathrm { L } {/tex}

C

{tex}22.4\ \mathrm { L } {/tex}

D

{tex}89.6\ L {/tex}

Explanation



Q 5.    

Correct4

Incorrect-1

{tex}25\ \mathrm { ml } {/tex} of a solution of barium hydroxide on titration with a {tex}0.1{/tex} molar solution of hydrochloric acid gave a litre value of {tex} 35\ \mathrm { ml } {/tex} . The molarity of barium hydroxide solution was

A

{tex} 0.14 {/tex}

B

{tex}0.28{/tex}

C

{tex}0.35{/tex}

{tex}0.07{/tex}

Explanation



Q 6.    

Correct4

Incorrect-1

{tex} 6.02 \times 10 ^ { 20 } {/tex} molecules of urea are present in {tex} 100\ \mathrm { ml } {/tex} of its solution. The concentration of urea solution is

A

{tex}0.02\ \mathrm { M } {/tex}

{tex}0.01 \ \mathrm { M } {/tex}

C

{tex}0.001\ \mathrm { M } {/tex}

D

{tex} 0.1\ \mathrm { M } {/tex}

Explanation



Q 7.    

Correct4

Incorrect-1

To neutralise completely {tex}20\ \mathrm { mL } {/tex} of {tex} 0.1\ \mathrm { M } {/tex} aqueous solution of phosphorous acid {tex} \left( \mathrm { H } _ { 3 } \mathrm { PO } _ { 3 } \right) , {/tex} the value of {tex} 0.1\ \mathrm { M } {/tex} aqueous {tex} \mathrm { KOH } {/tex} solution required is

{tex}40\ \mathrm { mL } {/tex}

B

{tex} 20\ \mathrm { mL } {/tex}

C

{tex}10\ \mathrm { mL } {/tex}

D

{tex}60\ \mathrm { mL } {/tex}

Explanation

Q 8.    

Correct4

Incorrect-1

The ammonia evolved from the treatment of {tex} 0.30\ \mathrm { g } {/tex} of an organic compound for the estimation of nitrogen was passed in {tex}100\ \mathrm { mL } {/tex} of {tex}0.1\ \mathrm { M } {/tex} sulphuric acid. The excess of acid required
{tex} 20\ \mathrm { mL } {/tex} of {tex}0.5\ \mathrm { M } {/tex} sodium hydroxide solution for complete neutralization. The organic compound is

urea

B

benzamide

C

acetamide

D

thiourea

Explanation









Q 9.    

Correct4

Incorrect-1

Two solutions of a substance (non electrolyte) are mixed in the following manner. {tex}480\, \mathrm { ml } {/tex} of {tex} 1.5\mathrm { M } {/tex} first solution {tex} +520 \mathrm { ml } {/tex} of {tex}1.2\ \mathrm { M } {/tex} second solution. What is the molarity of the final mixture?

A

{tex}2.70 \ \mathrm { M } {/tex}

{tex}1.344\ \mathrm { M } {/tex}

C

{tex} 1.50\ \mathrm { M } {/tex}

D

{tex}1.20\ \mathrm { M } {/tex}

Explanation





Q 10.    

Correct4

Incorrect-1

If we consider that {tex} 1 / 6 , {/tex} in place of {tex} 1 / 12 , {/tex} mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of the substance will

A

be a function of the molecular mass of the substance

B

remain unchanged

C

increase two fold

decrease twice

Explanation







Q 11.    

Correct4

Incorrect-1

How many moles of magnesium phosphate, {tex} \mathrm { Mg } _ { 3 } \left( \mathrm { PO } _ { 4 } \right) _ { 2 } {/tex} will contain {tex} 0.25\ \mathrm { mole } {/tex} of oxygen atoms?

A

{tex} 1.25 \times 10 ^ { - 2 } {/tex}

B

{tex} 2.5 \times 10 ^ { - 2 } {/tex}

C

{tex}0.02{/tex}

{tex} 3.125 \times 10 ^ { - 2 } {/tex}

Explanation



Q 12.    

Correct4

Incorrect-1

Density of a {tex}2.05\ \mathrm { M } {/tex} solution of acetic acid in water is {tex}1.02 \mathrm { g } / \mathrm { mL } {/tex} . The molality of the solution is

{tex} 2.28\ \mathrm { mol } \ \mathrm { kg } ^ { - 1 } {/tex}

B

{tex} 0.44\ \mathrm { mol } \ \mathrm { kg } ^ { - 1 } {/tex}

C

{tex}1.14\ \mathrm { mol } \ \mathrm { kg } ^ { - 1 } {/tex}

D

{tex}3.28\ \mathrm { mol }\ \mathrm { kg } ^ { - 1 } {/tex}

Explanation



Q 13.    

Correct4

Incorrect-1

{tex} \left. \text { The density (in g } \mathrm { mL } ^ { - 1 } \right) {/tex} of a {tex} 3.60 \ \mathrm { M } {/tex} sulphuric acid solution {tex} \left. \text { that is } 29 \%\ \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } \text { (molar mass } = 98 \mathrm {\ g\ mol } ^ { - 1 } \right) {/tex} by mass will be

A

1.45

B

1.64

C

1.88

1.22

Explanation





Q 14.    

Correct4

Incorrect-1

In the reaction,
{tex} 2 \mathrm { Al } ( \mathrm { s } ) + 6 \mathrm { HCl } ( \mathrm { aq } ) \rightarrow 2 \mathrm { Al } ^ { 3 + } ( \mathrm { aq } ) + 6 \mathrm { Cl } ^ { - } ( \mathrm { aq } ) + 3 \mathrm { H } _ { 2 } ( \mathrm { g } ) {/tex}

{tex} 11.2\ \mathrm { L }\ \mathrm { H } _ { 2 } ( \mathrm { g } ) {/tex} at {tex} \mathrm { STP } {/tex} is produced for every mole {tex} \mathrm { HCl } ( \mathrm { aq } ) {/tex} consumed

B

{tex} 6 \ \mathrm { L\ HCl } ( \mathrm { aq } ) {/tex} is consumed for every {tex}3\ \mathrm { LH } _ { 2 } ( \mathrm { g } ) {/tex} produced

C

{tex}33.6\ \mathrm { LH } _ { 2 } ( \mathrm { g }) {/tex} is produced regardless of temperature and pressure for every mole {tex} \mathrm { Al } {/tex} that reacts

D

{tex} 67.2\ \mathrm { H } _ { 2 } ( \mathrm { g } ) {/tex} at {tex} \mathrm { STP } {/tex} is produced for every mole {tex} \mathrm { Al } {/tex} that reacts.

Explanation

Q 15.    

Correct4

Incorrect-1

Consider the following reaction:
{tex} \mathrm { xMnO } _ { 4 } ^ { - } + \mathrm { yC } _ { 2 } \mathrm { O } _ { 4 } ^ { 2 - } + \mathrm { zH } ^ { + } \rightarrow \mathrm { xMn } ^ { 2 + } + 2 \mathrm { yCO } _ { 2 } + \frac { \mathrm { z } } { 2 } \mathrm { H } _ { 2 } \mathrm { O } {/tex}
The value's of {tex} x , y {/tex} and {tex} z {/tex} in the reaction are, respectively:

A

{tex} 5,2 {/tex} and {tex} 16 {/tex}

B

{tex} 2,5 {/tex} and {tex} 8 {/tex}

{tex} 2,5 {/tex} and {tex} 16 {/tex}

D

{tex} 5,2 {/tex} and {tex} 8 {/tex}

Explanation

Q 16.    

Correct4

Incorrect-1

A gaseous hydrocarbon gives upon combustion {tex}0.72{/tex} g of water and {tex} 3.08{/tex} g of {tex} \mathrm { CO } _ { 2 } {/tex} . The empirical formula of the hydrocarbon is:

A

{tex} \mathrm { C } _ { 2 } \mathrm { H } _ { 4 } {/tex}

B

{tex} \mathrm { C } _ { 3 } \mathrm { H } _ { 4 } {/tex}

C

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } {/tex}

{tex} \mathrm { C } _ { 7 } \mathrm { H } _ { 8 } {/tex}

Explanation



Q 17.    

Correct4

Incorrect-1

Experimentally it was found that a metal oxide has formula {tex} \mathrm { M } _ { 0.98 } \mathrm { O } {/tex} . Metal {tex} \mathrm { M } {/tex} , present as {tex} \mathrm { M } ^ { 2 + } {/tex} and {tex} \mathrm { M } ^ { 3 + } {/tex} in its oxide. Fraction of the metal which exists as {tex} \mathrm { M } ^ { 3 + } {/tex} would be :

A

{tex} 7.01\% {/tex}

{tex}4.08 \% {/tex}

C

{tex}6.05\ \% {/tex}

D

{tex}5.08 \% {/tex}

Explanation



Q 18.    

Correct4

Incorrect-1

Number of atoms in 558.5 gram Fe (at. wt. of {tex} \left. \mathrm { Fe } = 55.85 \mathrm { g } \mathrm { mol } ^ { - 1 } \right) {/tex} is

twice that in 60 g carbon

B

{tex} 6.023 \times 10 ^ { 22 } {/tex}

C

half that in 8 g He

D

{tex} 558.5 \times 6.023 \times 10 ^ { 23 } {/tex}

Explanation



Q 19.    

Correct4

Incorrect-1

With increase of temperature, which of thes changes?

A

Molality

B

Weight fraction of solute

Fraction of solute present in water

D

Mole fraction.

Explanation

Q 20.    

Correct4

Incorrect-1

What volume of hydrogen gas, at {tex} 273 \mathrm { K } {/tex} and 1 atm. pressure will be consumed in obtaining {tex} 21.6 \mathrm { g } {/tex} of elemental boron (atomic mass {tex} = 10.8 ) {/tex} from the reduction of boron trichloride by hydrogen?

A

89.6 {tex} \mathrm { L } {/tex}

67.2 {tex} \mathrm { L } {/tex}

C

44.8 {tex} \mathrm { L } {/tex}

D

22.4 {tex} \mathrm { L } {/tex}

Explanation



Q 21.    

Correct4

Incorrect-1

If we consider that {tex} 1 / 6 , {/tex} in place of {tex} 1 / 12 , {/tex} mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

decrease twice

B

increase two fold

C

remain unchanged

D

be a function of the molecular mass of the substance.

Explanation





Q 22.    

Correct4

Incorrect-1

How many moles of magnesium phosphate, {tex} \mathrm { Mg } _ { 3 } \left( \mathrm { PO } _ { 4 } \right) _ { 2 } {/tex} will contain 0.25 mole of oxygen atoms?

A

{tex} \mathrm 0.02{/tex}

{tex} 3.125 \times 10 ^ { - 2 } {/tex}

C

{tex} 1.25 \times 10 ^ { - 2 } {/tex}

D

{tex} 2.5 \times 10 ^ { - 2 } {/tex}

Explanation



Q 23.    

Correct4

Incorrect-1

In the reaction,
{tex} 2 \mathrm { Al } _ { ( s ) } + 6 \mathrm { HCl } _ { ( \alpha q ) } \rightarrow 2 \mathrm { Al } ^ { 3 + } ( a q ) + 6 \mathrm { Cl } ^ { - } _ { ( a g ) } + 3 \mathrm { H } _ { 2 ( \mathrm { g } ) } {/tex}

A

{tex} 11.2 \mathrm { LH } _ { 2 ( \mathrm { g } ) } {/tex} at {tex} \mathrm { STP } {/tex} is produced for every mole {tex} \mathrm { HCl } _ { ( a q ) } {/tex} consumed

B

{tex} 6 \mathrm { L } \mathrm { HCl } _ { ( \alpha q ) } {/tex} is consumed for every {tex} 3 \mathrm { L } \mathrm { H } _ { 2 ( g ) } {/tex} produced

33.6 {tex} \mathrm L \ \mathrm { H } _ { 2 ( \mathrm { g } ) } {/tex} is produced regardless of temperature and pressure for every mole Al that reacts

D

67.2 {tex} \mathrm { L }\ \mathrm { H } _ { 2 ( \mathrm { g } ) } {/tex} at {tex} \mathrm { STP } {/tex} is produced for every mole

Explanation

Q 24.    

Correct4

Incorrect-1

The total number of ions present in {tex} 1\ \mathrm { ml } {/tex} of {tex} 0.1\ \mathrm { M } {/tex} barium nitrate solution is

A

{tex} 6.02 \times 10 ^ { 8 } {/tex}

B

{tex} 6.02 \times 10 ^ { 10 } {/tex}

{tex} 3.0 \times 6.02 \times 10 ^ { 19 } {/tex}

D

{tex} 3.0 \times 6.02 \times 10 ^ { 8 } {/tex}

Explanation

Q 25.    

Correct4

Incorrect-1

Which of the following have lowest weight?

A

{tex} 6.023 \times 10 ^ { 22 } {/tex} molecules of glucose

B

{tex} 18 \mathrm { ml } {/tex} of water at {tex} 4 ^ { \circ } \mathrm { C } {/tex}

{tex} 11200 \mathrm { ml } {/tex} of {tex} \mathrm { CH } _ { 4 } {/tex} at STP

D

{tex} \mathrm {5.6\ litre} {/tex} of {tex} \mathrm { CO } _ { 2 } {/tex} at STP

Explanation