chemistry-Chemical Bonding – SARKARI LIBRARY

science

Which of these is NOT a type of chemical bond?

Ionic bond
Covalent bond
Metallic bond
Atomic bond

Explanation:

“Atomic bond” is not a standard classification; the primary types are ionic, covalent, and metallic.
An ionic bond involves the transfer of electrons between atoms.
A covalent bond involves the sharing of electron pairs between atoms.
A metallic bond is an attraction between positive metal ions and delocalized electrons.

What is the octet rule in chemical bonding?

Atoms lose all electrons to become stable.
Atoms tend to gain, lose, or share electrons to have 8 valence electrons.
Atoms bond to achieve zero net charge.
Atoms share protons to become stable.

Explanation:

The octet rule states that atoms are most stable when they have eight electrons in their outermost shell.
This is achieved through forming chemical bonds.
Exceptions include hydrogen and helium, which follow the duet rule.
Some elements in period 3 and beyond can have an expanded octet.

A bond formed by the equal sharing of electrons between two atoms is called?

Ionic bond
Non-polar covalent bond
Polar covalent bond
Coordinate bond

Explanation:

A non-polar covalent bond forms when two identical atoms share electrons equally (e.g., H₂, O₂).
An ionic bond involves complete electron transfer.
A polar covalent bond involves unequal sharing due to different electronegativities.
A coordinate bond is a type of covalent bond where both electrons come from one atom.

What type of bond holds the atoms in a water (H₂O) molecule together?

Ionic bond
Polar covalent bond
Non-polar covalent bond
Metallic bond

Explanation:

Water has polar covalent bonds due to the high electronegativity difference between oxygen and hydrogen.
This unequal sharing creates partial charges, making the molecule polar.
Ionic bonds are not present as electrons are shared, not transferred.
The bonds between different water molecules are hydrogen bonds, which are intermolecular forces.

Which compound is formed primarily by ionic bonding?

Methane (CH₄)
Water (H₂O)
Sodium Chloride (NaCl)
Hydrogen Gas (H₂)

Explanation:

Sodium Chloride (NaCl) is a classic ionic compound formed by electron transfer from sodium to chlorine.
Methane and water are covalent compounds.
Hydrogen gas has a non-polar covalent bond.
Ionic bonds typically form between metals and non-metals.

What is a coordinate covalent (dative) bond?

A bond with unequal sharing of electrons.
A bond between two metals.
A bond where both shared electrons are donated by one atom.
A very weak ionic bond.

Explanation:

In a coordinate bond, one atom provides both electrons for sharing (e.g., in NH₄⁺ or H₃O⁺).
Once formed, it is identical to any other covalent bond.
It is not specific to metals or defined by weakness.
Unequal sharing defines a polar covalent bond, not a coordinate bond.

The property of a metal to be drawn into wires is called?

Malleability
Conductivity
Ductility
Sonority

Explanation:

Ductility is the physical property of a material associated with the ability to be hammered thin or drawn into wires.
Malleability is the ability to be hammered or pressed into sheets.
Conductivity is the ability to conduct heat and electricity.
Sonority is the ability to produce a ringing sound when struck.

Which molecule has a triple covalent bond?

Oxygen (O₂)
Methane (CH₄)
Nitrogen (N₂)
Water (H₂O)

Explanation:

Nitrogen gas (N₂) has a triple covalent bond between the two nitrogen atoms.
Oxygen (O₂) has a double bond.
Methane (CH₄) has four single covalent bonds.
Water (H₂O) has two single polar covalent bonds.

What is the main principle behind VSEPR theory?

Atoms bond to achieve neutrality.
Electron pairs around a central atom repel each other to maximize distance.
Bonds form to complete the inner shell of electrons.
Electrons are transferred to create ions.

Explanation:

Valence Shell Electron Pair Repulsion (VSEPR) theory states that electron pairs (bonding and non-bonding) arrange themselves to minimize repulsion.
This determines the shape (geometry) of the molecule.
It is not related to achieving neutrality or transferring electrons.
The focus is on the arrangement of electron pairs in the valence shell.

Which of these is a property of ionic compounds?

Low melting and boiling points
Exist as gases or liquids at room temperature
High melting and boiling points
Are poor conductors in solid and molten state

Explanation:

Ionic compounds have high melting and boiling points due to the strong electrostatic forces holding the ions together.
They are crystalline solids at room temperature.
They are poor conductors in solid state but good conductors when molten or dissolved in water.
Low melting points are characteristic of covalent molecular compounds.

What is the shape of a molecule with 4 bonding pairs and no lone pairs?

Trigonal pyramidal
Bent
Tetrahedral
Linear

Explanation:

A central atom with 4 bonding pairs and no lone pairs has a tetrahedral electron geometry and molecular shape (e.g., CH₄).
Trigonal pyramidal is for 3 bonding pairs and 1 lone pair (e.g., NH₃).
Bent is for 2 bonding pairs and 1 or 2 lone pairs (e.g., H₂O).
Linear is for 2 bonding pairs and 0 lone pairs or 2 lone pairs (e.g., CO₂).

Which element has the highest electronegativity?

Chlorine
Oxygen
Fluorine
Nitrogen

Explanation:

Fluorine is the most electronegative element on the Pauling scale with a value of 4.0.
Electronegativity increases across a period and decreases down a group.
Chlorine (3.0), Oxygen (3.5), and Nitrogen (3.0) have lower values.
Electronegativity determines the polarity of a covalent bond.

What is the primary force holding molecules in a covalent network solid together?

Weak intermolecular forces
Electrostatic forces
A continuous network of covalent bonds
Metallic bonds

Explanation:

Covalent network solids (e.g., diamond, quartz) are giant molecules where atoms are bonded in a continuous network by strong covalent bonds.
This makes them very hard and have high melting points.
Electrostatic forces hold ionic solids together.
Weak intermolecular forces hold molecular solids together.

Which of these best describes a metallic bond?

Sharing of electron pairs
Transfer of electrons
Attraction between positive ions and a ‘sea’ of delocalized electrons
Sharing of protons

Explanation:

In metallic bonding, the metal atoms lose valence electrons to form positive ions. These electrons are delocalized and move freely, attracting the positive ions.
Sharing electron pairs defines covalent bonding.
Transfer of electrons defines ionic bonding.
This model explains properties like malleability and electrical conductivity.

What is the valency of the element with atomic number 15?

2
3
3 and 5
1

Explanation:

Atomic number 15 is Phosphorus (P). Its electron configuration is 2,8,5. It can gain 3 electrons to complete its octet (valency 3) or share 5 electrons in some cases (valency 5).
Valency is the combining capacity of an element.
It is determined by the number of valence electrons.

A molecule with a polar covalent bond must:

Be linear in shape
Be soluble in water
Have atoms with different electronegativities
Be an ionic compound

Explanation:

A polar covalent bond forms when two atoms with different electronegativities share electrons unequally.
The shape of the molecule determines if the bond dipoles cancel out (making the molecule non-polar) or not (making it polar).
Not all molecules with polar bonds are soluble in water (e.g., oil).
Ionic compounds involve electron transfer, not sharing.

Which theory explains the directional nature of a covalent bond?

VSEPR Theory
Valence Bond (VB) Theory
Molecular Orbital Theory
Bohr’s Theory

Explanation:

Valence Bond Theory explains covalent bond formation through the overlapping of atomic orbitals, which gives the bond its direction.
VSEPR Theory predicts the shape of the molecule after the bonds are formed.
Molecular Orbital Theory describes the electron structure of molecules in terms of molecular orbitals.
Bohr’s Theory is a model for the hydrogen atom.

Which intermolecular force is the strongest?

London Dispersion forces
Dipole-Dipole forces
Hydrogen bonding
Ion-Dipole forces

Explanation:

Hydrogen bonding is a strong type of dipole-dipole attraction that occurs when hydrogen is bonded to highly electronegative atoms (N, O, F).
It is responsible for the high boiling point of water.
London forces are the weakest and exist in all molecules.
Ion-Dipole forces are strong but are not typically classified with the main three intermolecular forces.

What is a sigma (σ) bond?

A bond formed by sidewise overlapping of orbitals
A bond formed by head-on overlapping of orbitals along the bond axis
A type of ionic bond
A very weak covalent bond

Explanation:

A sigma bond is the strongest type of covalent bond, formed by the end-to-end (axial) overlap of atomic orbitals.
Every single bond is a sigma bond.
A pi (π) bond is formed by the sidewise (lateral) overlap of p-orbitals and is present in multiple bonds.
It is not related to ionic bonding.

Which compound exhibits hydrogen bonding?

Hydrogen Sulphide (H₂S)
Hydrochloric Acid (HCl)
Ammonia (NH₃)
Methane (CH₄)

Explanation:

Ammonia (NH₃) has a hydrogen atom bonded to the highly electronegative nitrogen (N), allowing for hydrogen bonding.
H₂S and HCl have less electronegative atoms (S, Cl) and do not form significant hydrogen bonds.
Methane (C-H bonds) has no highly electronegative atom and cannot form hydrogen bonds.

What is the bond order in an oxygen (O₂) molecule?

Explanation:

Bond order = (Number of bonding electrons – Number of antibonding electrons)/2.
For O₂ (16 electrons), the molecular orbital configuration has 10 bonding and 6 antibonding electrons. Bond order = (10-6)/2 = 2.
Bond order indicates the strength and stability of a bond; a higher bond order means a stronger, shorter bond.

Which of these is an example of an interstitial alloy?

Brass
Bronze
Steel
Solder

Explanation:

Steel is an interstitial alloy where small carbon atoms fit into the interstices (gaps) between the larger iron atoms.
Brass (Cu-Zn) and Bronze (Cu-Sn) are substitutional alloys, where atoms of one metal replace atoms of another.
Solder is also typically a substitutional alloy.

According to Fajan’s Rules, covalent character is favored when:

The cation is large and the anion is small
Both ions are large
The cation is small and has a high positive charge
The anion is large and has a low negative charge

Explanation:

Fajan’s Rules state that a small cation with high charge density polarizes a large anion easily, distorting its electron cloud and introducing covalent character to the ionic bond.
A large cation and small anion favor pure ionic character.
This explains why some ionic compounds (like LiI) have significant covalent character.

What is the main component of LPG (Liquefied Petroleum Gas)?

Methane
Ethanol
Butane
Propane

Explanation:

LPG is primarily a mixture of hydrocarbon gases, most commonly butane (C₄H₁₀) and propane (C₃H₈).
It is stored under pressure as a liquid and used as fuel.
Methane is the main component of natural gas (CNG).
Ethanol is an alcohol, not a gas at room temperature.

Which vitamin is essential for blood clotting?

Vitamin A
Vitamin C
Vitamin D
Vitamin K

Explanation:

Vitamin K is a fat-soluble vitamin that plays a key role in helping the blood clot and preventing excessive bleeding.
Vitamin A is for vision and immune function.
Vitamin C is for collagen synthesis and immune function.
Vitamin D is for calcium absorption and bone health.

What is the SI unit of luminous intensity?

Watt
Lumen
Candela
Lux

Explanation:

The candela (cd) is the SI base unit of luminous intensity, which is the power emitted by a light source in a particular direction.
Watt is the unit of power.
Lumen is the unit of luminous flux (total perceived power).
Lux is the unit of illuminance (luminous flux per unit area).