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CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313673 Assertion :
Lattice enthalpy of $NaCl$ is $788 kJ$ ${mol}^{- 1}$ .
Reason :
$NaCl$ is a solid with 3D crystal structure.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

The lattice enthalpy of $NaCl$ (sodium chloride) is $788 kJ / mol$ . The sodium cations and chloride anions are held together in a crystal lattice by strong electrostatic forces of attraction due to their opposite charges. So it is a solid. Both the statements are correct but reason is not the correct explanation. So the option (2) is correct.

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313674 Which of the following substance has the highest melting point?

1

BaO

2

MgO

3

KCl

4

NaCl

Explanation:

Melting point depends upon lattice energy. $NaCl$ and $KCl$ have unit charge on their ions while $MgO$ and $BaO$ have two units of charge, therefore lattice energies of $MgO$ and $BaO$ are expected to be larger than those of $NaCl$ and $KCl$ Since, ${Mg}^{2 +}$ is smaller than ${Ba}^{2 +}$ , therefore, $MgO$ has the higher lattice energy and hence $MgO$ has the highest melting point.

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313675 Lattice energy depends on

1 Only radius of cation

2 Only radius of anion

3 Cation to anion radius ratio

4 Sum of the radii of cation and anion

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313673 Assertion :
Lattice enthalpy of $NaCl$ is $788 kJ$ ${mol}^{- 1}$ .
Reason :
$NaCl$ is a solid with 3D crystal structure.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

The lattice enthalpy of $NaCl$ (sodium chloride) is $788 kJ / mol$ . The sodium cations and chloride anions are held together in a crystal lattice by strong electrostatic forces of attraction due to their opposite charges. So it is a solid. Both the statements are correct but reason is not the correct explanation. So the option (2) is correct.

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313674 Which of the following substance has the highest melting point?

1

BaO

2

MgO

3

KCl

4

NaCl

Explanation:

Melting point depends upon lattice energy. $NaCl$ and $KCl$ have unit charge on their ions while $MgO$ and $BaO$ have two units of charge, therefore lattice energies of $MgO$ and $BaO$ are expected to be larger than those of $NaCl$ and $KCl$ Since, ${Mg}^{2 +}$ is smaller than ${Ba}^{2 +}$ , therefore, $MgO$ has the higher lattice energy and hence $MgO$ has the highest melting point.

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313675 Lattice energy depends on

1 Only radius of cation

2 Only radius of anion

3 Cation to anion radius ratio

4 Sum of the radii of cation and anion

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313673 Assertion :
Lattice enthalpy of $NaCl$ is $788 kJ$ ${mol}^{- 1}$ .
Reason :
$NaCl$ is a solid with 3D crystal structure.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

The lattice enthalpy of $NaCl$ (sodium chloride) is $788 kJ / mol$ . The sodium cations and chloride anions are held together in a crystal lattice by strong electrostatic forces of attraction due to their opposite charges. So it is a solid. Both the statements are correct but reason is not the correct explanation. So the option (2) is correct.

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313674 Which of the following substance has the highest melting point?

1

BaO

2

MgO

3

KCl

4

NaCl

Explanation:

Melting point depends upon lattice energy. $NaCl$ and $KCl$ have unit charge on their ions while $MgO$ and $BaO$ have two units of charge, therefore lattice energies of $MgO$ and $BaO$ are expected to be larger than those of $NaCl$ and $KCl$ Since, ${Mg}^{2 +}$ is smaller than ${Ba}^{2 +}$ , therefore, $MgO$ has the higher lattice energy and hence $MgO$ has the highest melting point.

CHXI04:CHEMICAL BONDING AND MOLECULAR STRUCTURE

313675 Lattice energy depends on

1 Only radius of cation

2 Only radius of anion

3 Cation to anion radius ratio

4 Sum of the radii of cation and anion