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Chemical Bonding

Description: This test contains 25 multiple choice questions on chemical bonding.
Number of Questions: 25
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Tags: Atoms molecules.mole.molarity etc. Ionic Bond: Lattice Energy
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Electrovalent compounds do not dissolves in organic solvents but dissolves in water. What makes ionic compounds soluble in water?

  1. Dielectric constant

  2. London forces

  3. Nuclear forces

  4. Electrostatic force


Correct Option: A
Explanation:

Electrovalent compounds or ionic compounds are usually soluble in water, but insoluble in organic solvents like ether, acetone, benzene, carbon disulphide and carbon tetrachloride. 'Like dissolves like': Ionic compounds dissolve in polar or ionic solvents. Water has a high dielectric constant. Water easily breaks the strong electrostatic force of attraction. The water molecule is polar in nature. The positively charged hydrogen atoms surround the anion. The negatively charged OH- (hydroxyl) surround the cation. Hence, the cation is separated from the anion, breaking the crystal lattice. The organic solvents contain non-polar molecules. Therefore, they are unable to break the electrostatic forces of attraction.

In the solid state, the electrovalent compounds do not conduct electricity because they are held strongly by:

  1. London forces

  2. Electrostatic forces

  3. Nuclear forces

  4. Van der waals forces


Correct Option: B
Explanation:

Ionic compounds conduct electricity when dissolved in water. They also conduct electricity when melted. They do not conduct electricity in the solid state. In the solid state, the ions are held together in fixed positions by the electrostatic forces of attraction. Therefore, the ions are not free.

The high density of ionic compounds results from:

  1. London force

  2. Nuclear forces

  3. Van der Walls forces

  4. Electrostatic forces


Correct Option: D
Explanation:

Ionic compounds have a high density. They are generally heavier than water. The oppositely charged ions in an ionic compound are held very closely by strong electrostatic forces of attraction, resulting in the number of ions per unit volume increases. Consequently, increasing in mass per unit volume of the compound.

The nonpolar substances condenses into liquids and then freezes into solids by:

  1. London force

  2. Electrostatic force

  3. Van der Waals forces

  4. Nuclear forces


Correct Option: A
Explanation:

The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction. London forces are the attractive forces that cause nonpolar substances to condense to liquids and to freeze into solids when the temperature is lowered sufficiently.

A cation:

  1. gains electrons

  2. loses electrons

  3. remains same

  4. becomes infinite


Correct Option: B
Explanation:

Size of the cation involved in bonding is smaller compared to the neutral atom. A cation loses electrons, so there is a reduction in the number of shells. Hence, the size of the ion becomes smaller.

Which of the following is not a property of an ionic solid?

  1. Occurs as hard crystalline solids

  2. Have high melting and boiling points

  3. Insoluble in organic solvents

  4. None of these


Correct Option: D
Explanation:

All are the properties of ionic solids.

The radius of a cation is:

  1. larger than the neutral atom

  2. similar to that of neutral atom

  3. smaller than the neutral atom

  4. doubles the radius of the atom


Correct Option: C
Explanation:

Size of the cation involved in bonding is smaller compared to the neutral atom. A cation loses electrons, so there is a reduction in the number of shells. Hence, the size of the ion becomes smaller.

Which among the following is strongest force?

  1. London dispersion force

  2. Electrostatic force

  3. Van der Waals forces

  4. Nuclear forces


Correct Option: D
Explanation:

As its name implies, it is the strongest force of the four. However, it also has the shortest range, meaning that particles must be extremely close before its effects are felt. Its main job is to hold together the subatomic particles of the nucleus (protons, which carry a positive charge, and neutrons, which carry no charge. These particles are collectively called nucleons.

Which of the following statement is wrong regarding the ionic bonds?

  1. Both metal & non metal is involved

  2. The electrostatic force works between the two charges

  3. Electron are shared between the atoms

  4. Ions are formed


Correct Option: C
Explanation:

The covalent bonding occurs when two (or more) elements share electrons. Covalent bonding occurs because the atoms in the compound have a similar tendency for electrons (generally to gain electrons). The ionic bonding is a one in which a complete transfer of electrons takes place between the atoms.

Which one is not correct regarding the ionic compounds?

  1. High melting and boiling points

  2. High electrical conductivity

  3. High rates of reactions

  4. Shows isomerism


Correct Option: D
Explanation:

Due to non-directional nature of the polar bonds present in these compounds they do not exhibit isomerism.

The formation of magnesium nitride involves:

  1. covalent bonding

  2. ionic bonding

  3. hydrogen bonds

  4. dative bond


Correct Option: B
Explanation:

A magnesium atom needs to lose two electrons, whereas the nitrogen atom needs to gain three electrons to attain the octet.The chemical formula for magnesium nitride is Mg3N2. Two magnesium atoms donate two electrons to each nitrogen atom while one magnesium atom donates one electron to each of the nitrogen atom. Hence, an ionic bond is formed. Magnesium and nitrogen, thus, attain stability by gaining the octet state.

The false statement, regarding the covalent compounds is:

  1. have low melting and boiling points

  2. are insoluble or less soluble in water

  3. are good conductors

  4. undergoes molecular reactions


Correct Option: C
Explanation:

Since covalent compounds do not give ions in solution, these are poor conductors of electricity in the fused or dissolved state.

The formation of ozone molecule involves:

  1. ionic bond

  2. covalent bond

  3. coordinate bond

  4. dipole moment


Correct Option: C
Explanation:

A molecule of oxygen contains two oxygen atoms joined by a double covalent bond.Thus, the two atoms of oxygen share two electrons each and do not require any more electrons because they have already attained stable octet configurations. If an atom of oxygen having six electrons comes closer to the oxygen molecule, the new atom may share a lone pair of electrons from either of these two oxygen atoms, which donates to the third oxygen atom without sharing any of the electrons of the third oxygen atom. As a result, a coordinate bond is formed between one of the oxygen atoms of the oxygen molecule, and the third atom of oxygen.

The forces directly proportional to the length of the nonpolar part of the substance is:

  1. London dispersion force

  2. Electrostatic force

  3. Nuclear forces

  4. Magnetic forces


Correct Option: A
Explanation:

The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction. Van der Waals-London forces grow with the length of the nonpolar part of the substance.

The dipole moment of CO2 is:

  1. 0

  2. 1.84 D

  3. 1.03 D

  4. 1.91


Correct Option: A
Explanation:

The dipole moment of carbon dioxide is zero. This is because CO2 is a linear molecule in which the two C=O (m=2.3D) bonds are oriented in opposite directions at an angle of 180°. Due to the linear geometry the dipole moment of one C = O bond cancels that of another. Therefore, the resultant dipole moment of the molecule is zero and it is a non-polar molecule.

Which of the following factors hinders formation of covalent bonds?

  1. High ionisation energy

  2. Equal electron affinity

  3. High nuclear charge and small atomic size

  4. None of these


Correct Option: D
Explanation:

All of the above factors favours the formayion of  covalent bonds.

Ionic compounds have high melting and boiling points because of:

  1. nuclear forces

  2. vander wall forces

  3. london dispersion force

  4. electrostatic forces


Correct Option: D
Explanation:

Ionic compounds have high melting and boiling points. For example, sodium chloride has a high melting point of 1472 oF and boiling point of 2575.4 oF. Lithium chloride has a melting point of 1122.8 oF and boiling point of 2462 oF. Potassium chloride has a melting point of 1526 oF and boiling point of 2732 oF. As these compounds contain ions held together by strong electrostatic forces, very high amount of energy is required to overcome this force and break the crystal lattice. This explains the high melting point and boiling point of ionic compounds.

Which one is not applicable for covalent solids?

  1. Directional character of bond

  2. Dissociates into ions

  3. Generally exists as molecules

  4. Undergoes molecular reactions


Correct Option: B
Explanation:

Since covalent compounds are made up of neutral molecules, if they dissolve in water they do not dissociate into ions. Example: Alcohol is soluble in water but does not dissociate to give ions.

A lone pair of electrons is present in:

  1. ioniic bond

  2. hydrogen bond

  3. co-ordinate bonding

  4. covalent bond


Correct Option: C
Explanation:

It is a special type of a covalent bond wherein the shared pair of electrons is supplied by only one of the bonding atoms. A lone pair of electrons is present in one of the atoms.e.g.Hydronium ion [H3O+ ] It is formed by the combination of water molecule and hydrogen ion. The oxygen atom in a water molecule has two lone pairs of electrons. It donates one pair to the hydrogen ion. Oxygen is thus the donor and hydrogen ion, the acceptor. The hydrogen ion carries over its charge to the hydronium ion.

NaCl has a definite shape because of:

  1. nuclear forces

  2. london force

  3. electrostatic force

  4. van der waal forces


Correct Option: C
Explanation:

Ionic compounds are hard crystalline solids. The crystal of sodium chloride has a definite shape. There is a strong electrostatic force of attraction, which holds the ions together. The ions cannot be easily separated. The crystals are hard and brittle.

A hydrogen when attached to an electronegative atom develops:

  1. hydrogen bond

  2. ionic bonds

  3. covalent bond

  4. dative bond


Correct Option: A
Explanation:

The hydrogen bond is really a special case of dipole forces. A hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine, which has a partial negative charge. The hydrogen then has the partial positive charge.

Which of the following wii help in the formation of anion?

  1. Low ionization energy

  2. Lower charge on the ion

  3. Larger atomic size

  4. High electronegativity and electron affinity


Correct Option: D
Explanation:

These measure the tendency of an atom to accept electrons. The atoms with high electronegativity and electron affinity readily form anion and hence ionic compounds.

Which one is unsuitable for cation formation?

  1. Low ionization energy

  2. High electronegativity and electron affinity

  3. Lower charge on the ion

  4. Larger atomic size


Correct Option: B
Explanation:

These measure the tendency of an atom to accept electrons. Therefore, atoms with high electronegativity and electron affinity readily form anion and hence ionic compounds.

Which one is unsuitable for anion formation?

  1. High electronegativity and electron affinity

  2. Smaller atomic size

  3. Low ionization energy

  4. Magnitude of charge on the ion


Correct Option: C
Explanation:

An atom with low ionization energy, readily loses electron. So it forms the cation readily and produce ionic compounds. Ex: Potassium gives the cation more readily than sodium because the ionization potential of potassium is less than the sodium atom.

The bond length is shortest in:

  1. triple covalent bond

  2. double covalent bond

  3. single covalent bond

  4. None of these


Correct Option: A
Explanation:

In a triple bond, six electrons attract the nuclei with greater force, out of the three types of bond length. This decreases the distance of separation between the two nuclei the most. Hence the bond length is shortest in triple bond.Since, a shorter bond means greater bond strength hence, the energy required to separate the bonded atoms is maximum.

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