All Free Chemistry MCQs with Answers

• A. He2+ is more stable than H2+.
• B. Bond dissociation energy of H2+ is more than bond dissociation energy of He2+.
• C. Since bond orders of He2+ and H2+ are equal, both will have equal bond dissociation energy.
• D. Bond length of H2+ is less than bond length of H2.

Explanation: The correct answer is that the bond dissociation energy of H2+ is more than that of He2+.

• A. Nitrogen bond pair electron cloud concentrates near the central atom because of its higher electronegativity, thus the bond pair - bond pair repulsion increases which in turn decreases the bond angle in NH3.
• B. Due to larger size of the lone pair electron cloud, there is larger lone pair - bond pair repulsion in PH3 compared to NH3.
• C. Due to the significant energy difference between 3s and 3p orbitals, the lone pair on phosphorous prefers to occupy an unhybridized s-orbital rather than a hybridized sp3 orbital.
• D. Phosphorous forms pπ - dπ bonds while nitrogen doesn't.

Explanation: The correct explanation for the difference in bond angles between PH3 and NH3 lies in the high energy difference between the 3s and 3p…

• A. dsp2, dsp3, sp2, sp3
• B. sp3, dsp2, dsp3, sp2
• C. dsp2, sp2, sp3, dsp3
• D. dsp2, sp3, sp2, dsp3

Explanation: The hybridization of the central atoms can be determined based on the number of electron pairs and geometry:NH3: The nitrogen atom forms…

• A. Lies in the plane of molecules
• B. A plane parallel to the molecular plane
• C. A plane perpendicular to the molecular plane which bisects the carbon−carbon σ−bond at right angle
• D. A plane perpendicular to the molecular plane which contains the carbon−carbon σ−bond.

Explanation: In ethene (C2H4), the π-bond is formed by the overlap of p-orbitals from each carbon atom.

• A. LiCl> BeCl2> BCl3> CCl4
• B. LiCl< BeCl2< BCl3< CCl4
• C. LiCl> BeCl2> CCl4> BCl3
• D. LiCl< BeCl3< BCl3> CCl4

Explanation: The correct order of covalent character among these compounds is LiCl < BeCl2 < BCl3 < CCl4.

• A. CFl4, SF4
• B. PCl3, BF3
• C. XeF2, CO2
• D. PF5, IF5

Explanation: The correct answer is XeF2 and CO2. Both of these molecules are linear, with bond angles of 180 degrees.

• A. These are generally in solid state at room temperature.
• B. The force of attraction between ions is non-directional.
• C. Ionic compounds are not always soluble in any polar solvent. It depends on the solvent.
• D. They conduct electricity in molten and solution state.

Explanation: Ionic compounds are not always soluble in any polar solvent. It depends on the solvent.

• A. HI
• B. HF
• C. HCl
• D. HBr

Explanation: The ionic character of a bond is directly related to the difference in electronegativity between the bonded atoms.

• A. Benzene
• B. Boron trifluoride
• C. Ethene
• D. Phosphorus trichloride

Explanation: Phosphorus trichloride does not have a planar geometry. It has a trigonal pyramidal molecular geometry.

• A. Al2O3 and Al2Cl6
• B. P4O10 and PCl3
• C. SiO2 and SiCl4
• D. HF and PbCl4

Explanation: Al2O3 (aluminum oxide) is a giant ionic compound. It consists of a three-dimensional lattice of aluminum ions (Al+3) and oxygen ions…

• A. NF3
• B. C3H8
• C. C2Cl4
• D. C3H6

Explanation: The molecule C3H8, which is propane, has only non-coplanar tetrahedral geometry.Propane (C3H8) consists of three carbon atoms bonded…

• A. Option A: The bond angle between CH3 and C is 1200.
• B. Option B: The bond angle between C and O is 1800.
• C. Option C: The bond angle between CH3 and C is 109.50 and between C and O is 1050.
• D. Option D: The bond angle between CH3 and C is 900.

Explanation: The angle P(between CH3 and C)is 109.50.The carbon atom in the methyl group forms tetrahedral angles due to its four single bonds…

• A. C2H4
• B. H2S
• C. CO2
• D. NCl3

Explanation: In the nitrogen trichloride molecule (NCl3), there are three single bonds between the nitrogen and chlorine atoms.

• A. Ammonia (NH3)
• B. Sulfur trioxide (SO3)
• C. Sulfate ion (SO42-)
• D. Sulfur dioxide (SO2)

Explanation: The sulfate ion (SO4-2) has a tetrahedral geometry. It consists of four oxygen atoms bonded to the central sulfur atom, forming a…

• A. Option A: C2H2 has two sigma (σ) bonds and two pi (π) bonds.
• B. Option B: C2H2 has two sigma (σ) bonds and one pi (π) bond.
• C. Option C: C2H2 has three sigma (σ) bonds and two pi (π) bonds.
• D. Option D: C2H2 has four sigma (σ) bonds and two pi (π) bonds.

Explanation: C2H2(acetylene) has a triple bond between the two carbon atoms, consisting of one sigma (σ) bond and two pi (π) bonds.

• A. Electronegativity difference
• B. Bond order
• C. S-character
• D. Number of lone pairs

Explanation: Lone pairs are non-bonding electron pairs present on an atom. They can exert repulsive forces on the electrons involved in neighboring…

• A. SO2
• B. CCl4
• C. SO3
• D. H2O

Explanation: Sulfur trioxide has a trigonal planar molecular geometry. It consists of three oxygen atoms bonded to a central sulfur atom, with no lone…

• A. CH3CHO
• B. CH3NH2
• C. CH3OH
• D. NH3

Explanation: Option A is correct.CH3CHO (acetone) will not form hydrogen bonds with another molecule of itself.

• A. Electron gas theory
• B. Valence bond theory
• C. Band theory
• D. Crystal field theory

Explanation: Option A is correct.Electron gas theory was put forward by Drude and extended by Loren (1923) to explain the properties of metallic solid.

• A. An electron
• B. A pair of electrons
• C. Three electrons
• D. Four electrons

Explanation: BF3 (boron trifluoride) is an electron pair acceptor because boron has an incomplete octet in its valence shell.