Some Basic Concepts Of Chemistry MCQ Test-1

1. A compound is a substance that contains

Two or more atoms of different elements

Two or more atoms of the same element

Two or mole molecules of same type

None of these

A compound is a substance that contains two or more atoms of different elements. This means that in a compound, there are at least two different types of atoms bonded together. Compounds are formed when atoms of different elements combine chemically to form a new substance with different properties than the individual elements. This is why the correct answer is "two or more atoms of different elements".

Explanation

A compound is a substance that contains two or more atoms of different elements. This means that in a compound, there are at least two different types of atoms bonded together. Compounds are formed when atoms of different elements combine chemically to form a new substance with different properties than the individual elements. This is why the correct answer is "two or more atoms of different elements".

2. Which one of the following is not homonuclear in nature-

N2

NH3

O2

Cl2

NH3 is not homonuclear in nature because it consists of different elements, nitrogen and hydrogen. Homonuclear molecules are composed of the same type of atoms, such as N2, O2, and Cl2, which are all made up of only one type of element.

Explanation

NH3 is not homonuclear in nature because it consists of different elements, nitrogen and hydrogen. Homonuclear molecules are composed of the same type of atoms, such as N2, O2, and Cl2, which are all made up of only one type of element.

3. Number of atoms present in NH₄are -

2

5

4

3

The correct answer is 5 because NH4 is the chemical formula for ammonium, which consists of one nitrogen atom (N) and four hydrogen atoms (H). Therefore, the total number of atoms present in NH4 is 5.

Explanation

The correct answer is 5 because NH4 is the chemical formula for ammonium, which consists of one nitrogen atom (N) and four hydrogen atoms (H). Therefore, the total number of atoms present in NH4 is 5.

4. A vessel contains 440 g of CO₂. It means that it is containing-

10 moles of CO2

6.022 x 1023 molecules of CO2

2.24 L of CO2 at STP

6.022 x 1023 atoms

The given statement suggests that the vessel contains 440 g of CO2, which is equivalent to 10 moles of CO2. This is because the molar mass of CO2 is approximately 44 g/mol, so dividing 440 g by 44 g/mol gives us 10 moles. Therefore, the vessel contains 10 moles of CO2.

Explanation

The given statement suggests that the vessel contains 440 g of CO2, which is equivalent to 10 moles of CO2. This is because the molar mass of CO2 is approximately 44 g/mol, so dividing 440 g by 44 g/mol gives us 10 moles. Therefore, the vessel contains 10 moles of CO2.

5. Which one will have maximum number of water molecules-

18 molecules of water

1.8 grams of water

18 grams of water

18 moles of water

The correct answer is 18 moles of water. A mole is a unit of measurement used in chemistry to represent a large number of particles, in this case, water molecules. One mole of any substance contains 6.022 x 10^23 particles. Therefore, 18 moles of water would contain 6.022 x 10^23 x 18 = 1.084 x 10^25 water molecules. Comparatively, 18 molecules of water, 1.8 grams of water, and 18 grams of water would have significantly fewer water molecules.

Explanation

The correct answer is 18 moles of water. A mole is a unit of measurement used in chemistry to represent a large number of particles, in this case, water molecules. One mole of any substance contains 6.022 x 10^23 particles. Therefore, 18 moles of water would contain 6.022 x 10^23 x 18 = 1.084 x 10^25 water molecules. Comparatively, 18 molecules of water, 1.8 grams of water, and 18 grams of water would have significantly fewer water molecules.

6. How many moles are present in 1.71 g of sucrose ( Mol. Wt. of sucrose = 342 g ) ?

1

0.05

5

0.005

The molar mass of sucrose is given as 342 g/mol. To calculate the number of moles, we divide the given mass (1.71 g) by the molar mass. So, 1.71 g / 342 g/mol = 0.005 mol. Therefore, there are 0.005 moles present in 1.71 g of sucrose.

Explanation

The molar mass of sucrose is given as 342 g/mol. To calculate the number of moles, we divide the given mass (1.71 g) by the molar mass. So, 1.71 g / 342 g/mol = 0.005 mol. Therefore, there are 0.005 moles present in 1.71 g of sucrose.

7. In a solution, mole fraction of solute is 0.32, then mole fraction of solvent will be-

1.0

0.32

0.58

0.68

The mole fraction of a solute in a solution represents the ratio of the moles of the solute to the total moles of both the solute and solvent. In this case, if the mole fraction of the solute is 0.32, it means that 0.32 moles of the solute are present for every mole of the solute and solvent combined. Since the mole fraction of the solvent is calculated by subtracting the mole fraction of the solute from 1, the mole fraction of the solvent would be 1 - 0.32 = 0.68.

Explanation

The mole fraction of a solute in a solution represents the ratio of the moles of the solute to the total moles of both the solute and solvent. In this case, if the mole fraction of the solute is 0.32, it means that 0.32 moles of the solute are present for every mole of the solute and solvent combined. Since the mole fraction of the solvent is calculated by subtracting the mole fraction of the solute from 1, the mole fraction of the solvent would be 1 - 0.32 = 0.68.

8. Choose the concentration method which is independent of temperature

Molarity

Molality

Normality

% v/v

Molality is the concentration method that is independent of temperature. It is defined as the number of moles of solute per kilogram of solvent. Unlike molarity and normality, which are dependent on temperature and can change with variations in volume and density, molality remains constant regardless of temperature. Therefore, molality is the correct answer as it is the only concentration method that is not affected by changes in temperature.

Explanation

Molality is the concentration method that is independent of temperature. It is defined as the number of moles of solute per kilogram of solvent. Unlike molarity and normality, which are dependent on temperature and can change with variations in volume and density, molality remains constant regardless of temperature. Therefore, molality is the correct answer as it is the only concentration method that is not affected by changes in temperature.

9. In 2 g of solid solute is added to 18 g of solvent, what is %w/w of the solution -

10 %

11.11 %

2 %

18 %

The %w/w of a solution is calculated by dividing the mass of the solute by the mass of the solution (solute + solvent) and multiplying by 100. In this case, 2 g of solid solute is added to 18 g of solvent, resulting in a total mass of 20 g. Therefore, the %w/w of the solution is (2 g / 20 g) * 100 = 10%.

Explanation

The %w/w of a solution is calculated by dividing the mass of the solute by the mass of the solution (solute + solvent) and multiplying by 100. In this case, 2 g of solid solute is added to 18 g of solvent, resulting in a total mass of 20 g. Therefore, the %w/w of the solution is (2 g / 20 g) * 100 = 10%.

10. Choose the correct descending order of entropy in the states of matter

Solid > Liquid > Gas

Gas > Solid > Liquid

Gas > Liquid > Solid

Liquid > Gas > Solid

The correct answer is Gas > Liquid > Solid. This is because gas has the highest entropy among the three states of matter. In the gas state, molecules are highly disordered and have the greatest amount of freedom to move around. In the liquid state, although molecules are still able to move around, they are more closely packed together compared to gas, resulting in lower entropy. In the solid state, molecules are tightly packed and have the least amount of freedom to move, leading to the lowest entropy.

Explanation

The correct answer is Gas > Liquid > Solid. This is because gas has the highest entropy among the three states of matter. In the gas state, molecules are highly disordered and have the greatest amount of freedom to move around. In the liquid state, although molecules are still able to move around, they are more closely packed together compared to gas, resulting in lower entropy. In the solid state, molecules are tightly packed and have the least amount of freedom to move, leading to the lowest entropy.

11. 20 g NaOH is dissolved in 200 mL of solution. What is the molarity of solution?

1.5 M

5 M

1 M

2.5 M

To find the molarity of a solution, we need to divide the number of moles of solute by the volume of the solution in liters. In this case, we have 20 grams of NaOH, which is a solute. To convert grams to moles, we divide by the molar mass of NaOH (22.99 g/mol + 16 g/mol + 1.01 g/mol = 40 g/mol). Therefore, we have 20 g / 40 g/mol = 0.5 moles of NaOH. The volume of the solution is given as 200 mL, which is equivalent to 0.2 liters. Dividing the number of moles by the volume in liters, we get 0.5 moles / 0.2 L = 2.5 Molarity.

Explanation

To find the molarity of a solution, we need to divide the number of moles of solute by the volume of the solution in liters. In this case, we have 20 grams of NaOH, which is a solute. To convert grams to moles, we divide by the molar mass of NaOH (22.99 g/mol + 16 g/mol + 1.01 g/mol = 40 g/mol). Therefore, we have 20 g / 40 g/mol = 0.5 moles of NaOH. The volume of the solution is given as 200 mL, which is equivalent to 0.2 liters. Dividing the number of moles by the volume in liters, we get 0.5 moles / 0.2 L = 2.5 Molarity.

12. The number of moles of moles in 0.224 litres of H₂ Gas at STP will be -

1

0.1

0.01

0.001

At STP (Standard Temperature and Pressure), one mole of any gas occupies a volume of 22.4 liters. Therefore, to find the number of moles in 0.224 liters of H2 gas, we divide the given volume by the volume of one mole at STP: 0.224/22.4 = 0.01 moles.

Explanation

At STP (Standard Temperature and Pressure), one mole of any gas occupies a volume of 22.4 liters. Therefore, to find the number of moles in 0.224 liters of H2 gas, we divide the given volume by the volume of one mole at STP: 0.224/22.4 = 0.01 moles.

13. Normality of 3 M H₂SO₄ solution is

3 N

6 N

9 N

12 N

The normality of a solution is defined as the number of equivalents of a solute present in one liter of the solution. In this case, the solution is a 3 M (molar) H2SO4 solution. Since H2SO4 is a diprotic acid, it can release two moles of H+ ions per mole of H2SO4. Therefore, the normality of the solution would be double the molarity, which is 6 N.

Explanation

The normality of a solution is defined as the number of equivalents of a solute present in one liter of the solution. In this case, the solution is a 3 M (molar) H2SO4 solution. Since H2SO4 is a diprotic acid, it can release two moles of H+ ions per mole of H2SO4. Therefore, the normality of the solution would be double the molarity, which is 6 N.

14. Which one of the following states of matter at an extensively high temperature

Solid

Liquid

Gas

Plasma

Bose Einstein Super Condensate State

Plasma is the correct answer because it is the state of matter that exists at an extensively high temperature. Plasma is formed when a gas is heated to such a high temperature that its atoms dissociate into ions and free electrons. This highly ionized gas is capable of conducting electricity and is often found in stars and lightning. Unlike solids, liquids, and gases, plasma does not have a definite shape or volume and is considered to be the most abundant state of matter in the universe.

Explanation

Plasma is the correct answer because it is the state of matter that exists at an extensively high temperature. Plasma is formed when a gas is heated to such a high temperature that its atoms dissociate into ions and free electrons. This highly ionized gas is capable of conducting electricity and is often found in stars and lightning. Unlike solids, liquids, and gases, plasma does not have a definite shape or volume and is considered to be the most abundant state of matter in the universe.

15. Which one of the following is not a homogeneous mixture-

Air

Smoke

Brass

Salt in water

Smoke is not a homogeneous mixture because it consists of tiny particles suspended in the air. These particles can vary in size and composition, resulting in an uneven distribution throughout the mixture. In contrast, air is a homogeneous mixture of gases, brass is a homogeneous mixture of copper and zinc, and salt in water forms a homogeneous solution.

Explanation

Smoke is not a homogeneous mixture because it consists of tiny particles suspended in the air. These particles can vary in size and composition, resulting in an uneven distribution throughout the mixture. In contrast, air is a homogeneous mixture of gases, brass is a homogeneous mixture of copper and zinc, and salt in water forms a homogeneous solution.

16. The molarity of a solution obtained by mixing 750 mL of 0.05 M HCl with 250 mL of 2 M HCl will be-

1.75 M

1.00 M

0.875 M

0.0975 M

When two solutions are mixed together, the resulting molarity can be calculated using the formula:

M1V1 + M2V2 = M3V3

Where M1 and V1 are the molarity and volume of the first solution, M2 and V2 are the molarity and volume of the second solution, and M3 is the resulting molarity.

In this case, the first solution has a molarity of 0.05 M and a volume of 750 mL, while the second solution has a molarity of 2 M and a volume of 250 mL.

Using the formula, we can calculate:

(0.05 M)(750 mL) + (2 M)(250 mL) = M3(1000 mL)

37.5 + 500 = M3(1000)

537.5 = M3(1000)

M3 = 537.5/1000

M3 = 0.5375 M

Therefore, the molarity of the resulting solution is 0.5375 M, which is closest to 0.875 M.

Explanation

When two solutions are mixed together, the resulting molarity can be calculated using the formula:

M1V1 + M2V2 = M3V3

Where M1 and V1 are the molarity and volume of the first solution, M2 and V2 are the molarity and volume of the second solution, and M3 is the resulting molarity.

In this case, the first solution has a molarity of 0.05 M and a volume of 750 mL, while the second solution has a molarity of 2 M and a volume of 250 mL.

Using the formula, we can calculate:

(0.05 M)(750 mL) + (2 M)(250 mL) = M3(1000 mL)

37.5 + 500 = M3(1000)

537.5 = M3(1000)

M3 = 537.5/1000

M3 = 0.5375 M

Therefore, the molarity of the resulting solution is 0.5375 M, which is closest to 0.875 M.

17. Chemistry is very important in human life. Choose the life saving drug-

Taxol

Aspirin

Paracetomol

Rantidine

Taxol is a correct answer because it is a life-saving drug used in chemotherapy to treat various types of cancer. It is derived from the bark of the Pacific yew tree and works by inhibiting the growth of cancer cells. Taxol is particularly effective in treating ovarian, breast, and lung cancers. Its importance in human life lies in its ability to prolong the lives of cancer patients and improve their quality of life.

Explanation

Taxol is a correct answer because it is a life-saving drug used in chemotherapy to treat various types of cancer. It is derived from the bark of the Pacific yew tree and works by inhibiting the growth of cancer cells. Taxol is particularly effective in treating ovarian, breast, and lung cancers. Its importance in human life lies in its ability to prolong the lives of cancer patients and improve their quality of life.

18. The number of atoms present in 11.2 litre of ozone (O₃) is -

3.011 x 1023

6.022 x 1023

9.033 x 1023

1.20 x 1023

not-available-via-ai

Explanation

not-available-via-ai

19. 149 g of KCl (Mol. Wt 74.5 g/mol ) is dissolved in 1000 g water. Density of solution given is 0.9 g/mL. The molarity and molality of the solution respectively is

1.8 M and 2 m

1.8 M and 1 m

1.567 M and 2 m

1.567 M and 1 m

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution in liters. In this case, we have 149 grams of KCl, which is equal to 149/74.5 = 2 moles of KCl. The volume of the solution is given as 1000 grams, which is equal to 1000/0.9 = 1111.11 mL or 1.1111 L. Therefore, the molarity of the solution is 2/1.1111 = 1.800 M.

The molality of a solution is calculated by dividing the moles of solute by the mass of the solvent in kilograms. In this case, the mass of water is given as 1000 grams, which is equal to 1000/1000 = 1 kilogram. Therefore, the molality of the solution is 2/1 = 2 m.

Hence, the correct answer is 1.567 M and 2 m.

Explanation

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution in liters. In this case, we have 149 grams of KCl, which is equal to 149/74.5 = 2 moles of KCl. The volume of the solution is given as 1000 grams, which is equal to 1000/0.9 = 1111.11 mL or 1.1111 L. Therefore, the molarity of the solution is 2/1.1111 = 1.800 M.

The molality of a solution is calculated by dividing the moles of solute by the mass of the solvent in kilograms. In this case, the mass of water is given as 1000 grams, which is equal to 1000/1000 = 1 kilogram. Therefore, the molality of the solution is 2/1 = 2 m.

Hence, the correct answer is 1.567 M and 2 m.

20. Equivalent weight of H₃PO₃ will be (atomic mass of P = 31 g/mol)

27.33 g

82 g

41 g

20.5 g

The equivalent weight of a compound is defined as the molar mass divided by the number of electrons transferred per molecule during a reaction. In the case of H3PO3, the molar mass of phosphorus (P) is 31 g/mol. Since H3PO3 can donate one hydrogen ion (H+) per molecule, the number of electrons transferred is 1. Therefore, the equivalent weight of H3PO3 is 31 g/mol divided by 1, which equals 31 g/mol.

Explanation

The equivalent weight of a compound is defined as the molar mass divided by the number of electrons transferred per molecule during a reaction. In the case of H3PO3, the molar mass of phosphorus (P) is 31 g/mol. Since H3PO3 can donate one hydrogen ion (H+) per molecule, the number of electrons transferred is 1. Therefore, the equivalent weight of H3PO3 is 31 g/mol divided by 1, which equals 31 g/mol.