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

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Some Basic Concepts of Chemistry

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Q 1. Suppose the elements X and Y combine to form two compounds XY{tex}_2{/tex} and X{tex}_3{/tex}Y{tex}_2{/tex}. When 0.1 mole of XY{tex}_2{/tex} weighs 10 g and 0.05 mole of X{tex}_3{/tex}Y{tex}_2{/tex} weighs 9 g, the atomic weights of X and Y are

{tex} 40,30 {/tex}

B

{tex} 60,40 {/tex}

C

{tex} 20,30 {/tex}

D

{tex} 30,20 {/tex}

Explanation

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Q 2. What is the mass of the precipitate formed when 50 mL of 16.9{tex} \% {/tex} solution of {tex} \mathrm { AgNO } _ { 3 } {/tex} is mixed with 50 mL of 5.8{tex} \% \ \mathrm { NaCl } {/tex} solution?
{tex} ( \mathrm { Ag } = 107.8 , \mathrm { N } = 14 , \mathrm { O } = 16 , \mathrm { Na } = 23, {/tex} {tex} \mathrm { Cl } = 35.5 ) {/tex}

A

3.5{tex} \mathrm { g } {/tex}

7{tex} \mathrm { g } {/tex}

C

14{tex} \mathrm { g } {/tex}

D

28{tex} \mathrm { g } {/tex}

Explanation

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Q 3. If Avogadro number {tex}N _ { A } , {/tex} is changed from {tex} 6.022 \times 10 ^ { 23 } \mathrm { mol } ^ { - 1 } {/tex} to {tex} 6.022 \times 10 ^ { 20 } \mathrm { mol } ^ { - 1 } , {/tex} this would change

the mass of one mole of carbon

B

the ratio of chemical species to each other in a balanced equation

C

the ratio of elements to each other in a compound

D

the definition of mass in units of grams.

Explanation

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Q 4. The number of water molecules is maximum in

A

1.8 gram of water

B

18 gram of water

18 moles of water

D

18 molecules of water.

Explanation

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Q 5. A mixture of gases contains {tex} \mathrm { H } _ { 2 } {/tex} and {tex} \mathrm { O } _ { 2 } {/tex} gases in the ratio of {tex} 1 : 4 ( w / w ) . {/tex} What is the molar ratio of the two gases in the mixture?

A

{tex} 16 : 1 {/tex}

B

{tex} 2 : 1 {/tex}

C

{tex} 1 : 4 {/tex}

{tex} 4 : 1 {/tex}

Explanation

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Q 6. Equal masses of {tex} \mathrm { H } _ { 2 } , \mathrm { O } _ { 2 } {/tex} and methane have been taken in a container of volume {tex}\mathrm V {/tex} at temperature {tex} 27 ^ { \circ } \mathrm { C } {/tex} in identical conditions. The ratio of the volumes of gases {tex} \mathrm { H } _ { 2 } : \mathrm { O } _ { 2 } : {/tex} methane would be

A

{tex} 8 : 16 : 1 {/tex}

B

{tex} 16 : 8 : 1 {/tex}

{tex} 16 : 1 : 2 {/tex}

D

{tex} 8 : 1 : 2 {/tex}

Explanation


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Q 7. When 22.4 litres of {tex} \mathrm { H } _ { 2 ( g ) } {/tex} is mixed with 11.2 litres of {tex} \mathrm { Cl } _ { 2 ( g ) } {/tex} , each at {tex} \mathrm { S.T.P }{/tex}, the moles of {tex} \mathrm { HCl } _ { ( g ) } {/tex} formed is equal to

1 mol of {tex} \mathrm { HCl } _ { ( g ) } {/tex}

B

2 mol of {tex} \mathrm { HCl } _ { ( \mathrm { g } ) } {/tex}

C

0.5 mol of {tex} \mathrm { HCl } _ { ( g ) } {/tex}

D

1.5 mol of {tex} \mathrm { HCl } _ { ( \mathrm { g } ) } {/tex}

Explanation

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Q 8. {tex}\mathrm{1.0 g}{/tex} of magnesium is burnt with {tex}\mathrm{0.56 g \ O_2}{/tex} in a closed vessel. Which reactant is left in excess and how much? (At.wt. {tex}\mathrm{Mg = 24,O = 16}{/tex} )

{tex} \mathrm { Mg } , 0.16 \mathrm { g } {/tex}

B

{tex} \mathrm { O } _ { 2 } , 0.16 \mathrm { g } {/tex}

C

{tex} \mathrm { Mg } , 0.44 \mathrm { g } {/tex}

D

{tex} \mathrm { O } _ { 2 } , 0.28 \mathrm { g } {/tex}

Explanation

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Q 9. {tex} 6.02 \times 10 ^ { 20 } {/tex} molecules of urea are present in {tex}\mathrm{100 mL}{/tex} of its solution. The concentration of solution is

A

{tex}\mathrm0.001 \mathrm { M } {/tex}

B

{tex}\mathrm0.1{tex} \mathrm { M } {/tex}

C

{tex}\mathrm0.02{tex} \mathrm { M } {/tex}

{tex}\mathrm0.01{tex} \mathrm { M } {/tex}

Explanation

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Q 10. In an experiment it showed that 10mL of 0.05{tex} \mathrm { M } {/tex} solution of chloride required 10 mL of 0.1{tex} \mathrm { M } {/tex} solution of {tex} \mathrm { AgNO } _ { 3 } {/tex} , which of the following will be the formula of the chloride {tex} ( X {/tex} stands for the symbol of the element other than chlorine)

A

{tex} X _ { 2 } \mathrm { Cl } _ { 2 } {/tex}

{tex} X \mathrm { Cl } _ { 2 } {/tex}

C

{tex} X \mathrm { Cl } _ { 4 } {/tex}

D

{tex} X _ { 2 } \mathrm { Cl } {/tex}

Explanation

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Q 11. Which has the maximum number of molecules among the following?

A

44{tex} \ \mathrm { g }\ \mathrm { CO } _ { 2 } {/tex}

B

48{tex}\ \mathrm { g } \ \mathrm { O } _ { 3 } {/tex}

8{tex} \ \mathrm { g } \ \mathrm { H } _ { 2 } {/tex}

D

64{tex}\ \mathrm { g } \ \mathrm { SO } _ { 2 } {/tex}

Explanation

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Q 12. The number of atoms in 0.1 mol of a triatomic gas is {tex} \left( N _ { A } = 6.02 \times 10 ^ { 23 } \mathrm { mol } ^ { - 1 } \right) {/tex}

A

{tex} 6.026 \times 10 ^ { 22 } {/tex}

{tex} 1.806 \times 10 ^ { 23 } {/tex}

C

{tex} 3.600 \times 10 ^ { 23 } {/tex}

D

{tex} 1.800 \times 10 ^ { 22 } {/tex}

Explanation

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Q 13. {tex}25.3 \mathrm { g } {/tex} of sodium carbonate, {tex} \mathrm { Na } _ { 2 } \mathrm { CO } _ { 3 } {/tex} is dissolved in enough water to make {tex}\mathrm {250 mL}{/tex} of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, {tex} \mathrm { Na } ^ { + } {/tex} and carbonate ions, {tex} \mathrm { CO } _ { 3 } ^ { 2 - } {/tex} are respectively (Molar mass of {tex} \mathrm { Na } _ { 2 } \mathrm { CO } _ { 3 } {/tex}= {tex}\mathrm {106 g mol}{tex}^ { - 1 }{/tex})

A

{tex}0.955 \mathrm { M } {/tex} and {tex}1.910 \mathrm { M } {/tex}

{tex}1.910 \mathrm { M } {/tex} and {tex}0.955 \mathrm { M } {/tex}

C

{tex}1.90 \mathrm { M } {/tex} and {tex}1.910{tex} \mathrm { M } {/tex}

D

{tex}0.477{tex} \mathrm { M } {/tex} and {tex}0.477{tex} \mathrm { M } {/tex}

Explanation


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Q 14. 10 {tex} \mathrm { g } {/tex} of hydrogen and 64{tex} \mathrm { g } {/tex} of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be

A

3 mol

4 mol

C

1 mol

D

2 mol

Explanation

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Q 15. What volume of oxygen gas {tex} \left( \mathrm { O } _ { 2 } \right) {/tex} measured at {tex} 0 ^ { \circ } \mathrm { C } {/tex} and 1{tex} \mathrm { atm } {/tex} , is needed to burn completely 1{tex} \mathrm { L } {/tex} of propane gas {tex} \left( \mathrm { C } _ { 3 } \mathrm { H } _ { 8 } \right) {/tex} measured under the same conditions?

5{tex} \mathrm { L } {/tex}

B

10{tex} \mathrm { L } {/tex}

C

7{tex} \mathrm { L } {/tex}

D

6{tex} \mathrm { L } {/tex}

Explanation

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Q 16. How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of {tex} \mathrm { PbO } {/tex} and 3.2 g {tex} \mathrm { HCl } {/tex} ?

A

0.011

0.029

C

0.044

D

0.333

Explanation

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Q 17. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave {tex} \mathrm { C } , 38.71 \% {/tex} and {tex} \mathrm { H } , 9.67 \% {/tex} . The empirical formula of the compound would be

A

{tex} \mathrm { CHO } {/tex}

B

{tex} \mathrm { CH } _ { 4 } \mathrm { O } {/tex}

{tex} \mathrm { CH } _ { 3 } \mathrm { O } {/tex}

D

{tex} \mathrm { CH } _ { 2 } \mathrm { O } {/tex}

Explanation

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Q 18. An element, {tex}X{/tex} has the following isotopic composition:
{tex}^{200}X : 90\%\ \ \ \ ^{199}X : 8.0\% \ \ \ \ ^{202}X : 2.0\% {/tex}
The weighted average atomic mass of the naturally occurring element {tex}X{/tex} is closest to

A

201 amu

B

202 amu

C

199 amu

200 amu

Explanation

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Q 19. The maximum number of molecules is present in

15 L of {tex}\mathrm {H_2}{/tex} gas at STP

B

5 L of {tex} \mathrm { N } _ { 2 } {/tex} gas at {tex} \mathrm { STP } {/tex}

C

0.5 g of {tex} \mathrm { H } _ { 2 } {/tex} gas

D

10{tex} \mathrm { g } {/tex} of {tex} \mathrm { O } _ { 2 } {/tex} gas.

Explanation


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Q 20. Which has maximum molecules?

A

{tex} 7g {/tex} {tex} \mathrm { N } _ { 2 } {/tex}

{tex}2g {/tex} {tex}\mathrm { H } _ { 2 } {/tex}

C

{tex}16g {/tex} {tex}\mathrm { NO } _ { 2 } {/tex}

D

{tex}16g {/tex} {tex}\mathrm { O } _ { 2 } {/tex}

Explanation

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Q 21. Percentage of Se in peroxidase anhydrous enzyme is 0.5{tex} \% {/tex} by weight (at. wt. = 78.4 ) then minimum molecular weight of peroxidase anhydrous enzyme is

{tex} 1.568 \times 10 ^ { 4 } {/tex}

B

{tex} 1.568 \times 10 ^ { 3 } {/tex}

C

{tex} 1.568 {/tex}

D

{tex} 2.136 \times 10 ^ { 4 } {/tex}

Explanation

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Q 22. Molarity of liquid HCl, if density of solution is 1.17 g/cc is

A

36.5

B

18.25

32.05

D

42.10

Explanation

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Q 23. Specific volume of cylindrical virus particle is {tex} 6.02 \times 10 ^ { - 2 } \mathrm { cc } / \mathrm { g } {/tex} whose radius and length are 7{tex} {\text{Å}} {/tex} and 10{tex} {\text{Å}} {/tex} respectively. If {tex} N _ { A } = 6.02 \times 10 ^ { 23 } {/tex} , find molecular weight of an virus.

{tex} 15.4 \ \mathrm { kg } / \mathrm { mol } {/tex}

B

{tex} 1.54 \times 10 ^ { 4 } \mathrm { kg } / \mathrm { mol } {/tex}

C

{tex} 3.08 \times 10 ^ { 4 } \mathrm { kg } / \mathrm { mol } {/tex}

D

{tex} 3.08 \times 10 ^ { 3 } \mathrm { kg } / \mathrm { mol } {/tex}

Explanation

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Q 24. In quantitative analysis of second group in laboratory, {tex}\mathrm{H_{2}S}{/tex} gas is passed in acidic medium for precipitation. When {tex}\mathrm{Cu}{tex} ^ { 2 + } {/tex} and {tex}\mathrm{Cd}{tex} ^ { 2 + } {/tex} react with {tex}\mathrm{ KCN} , {/tex} then for product, true statement is

A

{tex} \mathrm { K } _ { 2 } \left[ \mathrm { Cu } ( \mathrm { CN } ) _ { 4 } \right] {/tex} more soluble

B

{tex} \mathrm { K } _ { 2 } \left[ \mathrm { Cd } ( \mathrm { CN } ) _ { 4 } \right] {/tex} less stable

{tex} \mathrm { K } _ { 3 } \left[ \mathrm { Cu } ( \mathrm { CN } ) _ { 2 } \right] {/tex} less stable

D

{tex} \mathrm { K } _ { 2 } \left[ \mathrm { Cd } ( \mathrm { CN } ) _ { 3 } \right] {/tex} more stable.

Explanation


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Q 25. Volume of {tex} \mathrm { CO } _ { 2 } {/tex} obtained by the complete decomposition of 9.85{tex} \mathrm { g } {/tex} of {tex} \mathrm { BaCO } _ { 3 } {/tex} is

A

2.24{tex} \mathrm { L } {/tex}

1.12{tex} \mathrm { L } {/tex}

C

0.84{tex} L {/tex}

D

0.56{tex} \mathrm { L } {/tex}

Explanation