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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 experienced teachers.

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Some Basic Concepts of Chemistry

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Q 1. {tex} X {/tex} is molecular substance containing 21 atoms of carbon per molecule. The weight {tex} \% {/tex} of {tex} C {/tex} in {tex} X {/tex} is 50.4{tex} \% {/tex} . What is the molecular weight of {tex} X {/tex} in amu?

500

B

200

C

300

D

400

Explanation

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Q 2. The volume (in {tex} \mathrm { mL } ) {/tex} of 0.5{tex} \mathrm { M }\space \mathrm { NaOH } {/tex} required for the complete reaction with 150{tex} \mathrm { mL } {/tex} of 1.5{tex} \mathrm { M } \space\mathrm { H } _ { 3 } \mathrm { PO } _ { 3 } {/tex} solution is

A

1350

900

C

1250

D

1150

Explanation

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Q 3. For the reaction,
{tex} \mathrm { AlCl } _ { 3 } + \mathrm { NaOH } \longrightarrow \mathrm { Al } ( \mathrm { OH } ) _ { 3 } + \mathrm { NaCl } {/tex}
if initially, 1 mole of each reactant is taken, then the number of moles of {tex} \mathrm { AlCl } _ { 3 } {/tex} remaining after the completion of reaction is

A

1

B

{tex} \frac { 1 } { 3 } {/tex}

{tex} \frac { 2 } { 3 } {/tex}

D

None of these

Explanation

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Q 4. A mixture of {tex} \mathrm { CaCO } _ { 3 } {/tex} and {tex} \mathrm { CaO } {/tex} on heating gives off 22.4{tex} \mathrm { L } {/tex} of {tex} \mathrm { CO } _ { 2 } {/tex} gas at 273{tex} \mathrm { K } {/tex} and 1 atm. If the same mass of mixture when treated with {tex}\mathrm {HCl} {/tex} required 219{tex} \mathrm { g } {/tex} of {tex}\mathrm {HCl} {/tex} for complete reaction, then the mole {tex} \% {/tex} of {tex} \mathrm { CaCO } _ { 3 } {/tex} in the mixture is

A

50{tex} \% {/tex}

33.33{tex} \% {/tex}

C

25{tex} \% {/tex}

D

None of these

Explanation



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Q 5. The relative density of a mixture of {tex} \mathrm { CO } _ { 2 } ( \mathrm { g } ) {/tex} and {tex} \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { g } ) {/tex} w. r.t. gaseous hydrogen atoms is {tex} 30 . {/tex} The molecular {tex} \% {/tex} of the {tex} \mathrm { CO } _ { 2 } {/tex} is

{tex} \frac { 600 } { 13 } {/tex}

B

{tex} \frac { 2400 } { 13 } {/tex}

C

{tex} \frac { 1200 } { 13 } {/tex}

D

None of these

Explanation

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Q 6. 100 mL Of 0.1 M ammonium phosphite solution is mixed with 200 mL Of 0.2 M sodium pyrophosphate solution. Assuming complete dissociation of each salt and no reaction occurs between the ions produced, calculate the concentration Of total positive ions in millimoles per litre.

600

B

200

C

500

D

60

Explanation

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Q 7. Human lungs can absorb 8{tex} \mathrm { g } \space\mathrm { O } _ { 2 } {/tex} per hour by respiration. If all oxygen atoms are converted to carbohydrates {tex} \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 12 } \mathrm { O } _ { 6 } \right) , {/tex} how long will it take to produce 180 {tex} \mathrm { g }\space \mathrm { C } _ { 6 } \mathrm { H } _ { 12 } \mathrm { O } _ { 6 } ? {/tex}

A

8{tex} \mathrm { hr } {/tex}

12{tex} \mathrm { hr } {/tex}

C

10{tex} \mathrm { hr } {/tex}

D

6{tex} \mathrm { hr } {/tex}

Explanation

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Q 8. 100 g {tex} \space '118 \% \space oleum'{/tex} sample is mixed with 9{tex} \mathrm { g } {/tex} of {tex} \mathrm { H } _ { 2 } \mathrm { O } {/tex}. The final solution has

A

mass {tex} \% {/tex} of {tex} \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } {/tex} is 2.7

B

Mass {tex} \% {/tex} of combined {tex} \mathrm { SO } _ { 3 } {/tex} is 16.3

New labelling as 108.25{tex} \% {/tex} oleum.

D

Mass {tex} \% {/tex} of free {tex} \mathrm { SO } _ { 3 } {/tex} is 80

Explanation


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Q 9. 1 mole of ammonium phosphate will contain

A

2 moles of nitrogen atoms.

B

8 moles of hydrogen atoms.

12 moles of hydrogen atoms.

D

6 moles of hydrogen atoms.

Explanation

1 mole of ammonium phosphate contains 12 moles of hydrogen atoms.

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Q 10. Find the total number of carbon atom present in one molecule, if 0.078 g hydrocarbon having simplest formula unit {tex} \mathrm { CH } {/tex} , occupy 22.4{tex} \mathrm { mL } {/tex} of volume at 1{tex} \mathrm { atm } {/tex} and {tex} 0 ^ { \circ } \mathrm { C } . {/tex}

A

5

B

4

C

2

6

Explanation

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Q 11. Find volume occupied by 1 molecule of {tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OCH } _ { 3 } {/tex} having density of {tex} 0.8 \mathrm \space { g } / \mathrm { cm } ^ { 3 } . {/tex}
{tex} \left[ \text { Given } : N _ { A } = 6 \times 10 ^ { 23 } \right] {/tex}

{tex} 1.25 \times 10 ^ { - 22 } \mathrm { cm } ^ { 3 } {/tex}

B

{tex} 2.25 \times 10 ^ { - 22 } \mathrm { cm } ^ { 3 } {/tex}

C

{tex} 3.25 \times 10 ^ { - 22 } \mathrm { cm } ^ { 3 } {/tex}

D

{tex} 1.00 \times 10 ^ { - 22 } \mathrm { cm } ^ { 3 } {/tex}

Explanation

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Q 12. 1 mole of diatomic gas {tex} A _ { 2 } {/tex} contains 32 and 36 moles of electrons and neutrons respectively. Find the mass number of element {tex} A {/tex} .

A

32

B

68

C

40

34

Explanation


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Q 13. Find the number of moles of {tex} \mathrm { Na } _ { 3 } \mathrm { PO } _ { 4 } {/tex} which contain as many ions as present in 6840{tex} \mathrm { g } {/tex} of {tex} \mathrm { Al } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } {/tex} .

A

20

25

C

30

D

60

Explanation

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Q 14. Find the correct option for 36{tex} \mathrm { g } \space \mathrm { C } _ { 6 } \mathrm { H } _ { 12 } \mathrm { O } _ { 6 } {/tex}

A

4.8 {tex} \mathrm { N } _ { \mathrm { A } } {/tex} molecules of {tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 12 } \mathrm { O } _ { 6 } {/tex}

19.2 {tex} \mathrm { N } _ { \mathrm { A } } {/tex} electrons

C

0.8 moles

D

0.6 g molecules of oxygen

Explanation

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Q 15. Find the number of iodine atoms present in 40{tex} \footnotesize \mathrm { mL } {/tex} of its 0.1{tex} \footnotesize \mathrm { M } {/tex} solution.

{tex} 48.17 \times 10 ^ { 20 } {/tex}

B

{tex} 4.81 \times 10 ^ { 20 } {/tex}

C

{tex} 6.02 \times 10 ^ { 23 } {/tex}

D

None of these

Explanation

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Q 16. If one million atoms of silver weight is {tex} 1.79 \times 10 ^ { - 16 } \mathrm { g } {/tex} , the gram atomic mass of silver is

A

107{tex} \mathrm { g } {/tex}

B

107.2{tex} \mathrm { g } {/tex}

107.8{tex} \mathrm { g } {/tex}

D

108.2{tex} \mathrm { g } {/tex}

Explanation

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Q 17. The mole fraction of glucose in aqueous solution is {tex} 0.2 , {/tex} then molality of solution will be

13.8

B

55.56

C

2

D

12

Explanation

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Q 18. Molality of pure water is

A

1

55.56

C

20

D

Cannot be calculated

Explanation

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Q 19. Ammonia gas is passed into water, yielding a solution of density {tex}\mathrm {0.93\ g/ cm } ^ { 3 } {/tex} and containing {tex} 18.6 \%\ \mathrm { NH } _ { 3 } {/tex} by weight. The mass of {tex} \mathrm { NH } _ { 3 } {/tex} per cc of the solution is

{tex} 0.17\ \mathrm { g } / \mathrm { cm } ^ { 3 } {/tex}

B

{tex} 0.34\ \mathrm { g } / \mathrm { cm } ^ { 3 } {/tex}

C

{tex} 0.51\ \mathrm { g } / \mathrm { cm } ^ { 3 } {/tex}

D

{tex} 0.68\ \mathrm { g } / \mathrm { cm } ^ { 3 } {/tex}

Explanation