Problem 128
Which of the following combinations is not allowed in the LC \(\Lambda O\) method for the formation of a MO (consider the \(z\) -axis as the molecular axis?? (1) \(\mathrm{s}+\mathrm{p}_{2}\) (2) \(\mathrm{s}-\mathrm{p}_{x}\) (3) \(\mathrm{p}_{x}-\mathrm{p}_{x}\) (4) \(\mathrm{p}_{2}+\mathrm{p}_{z}\)
Problem 129
The energy of \(2 \mathrm{~s}\) is greater than \(\sigma^{*} 1 \mathrm{~s}\) orbital because (1) \(\sigma 2 \mathrm{~s}\) -orbital is bigger than \(\sigma\) /s-orbital. (2) \(\sigma 2 \mathrm{~s}\) is a bonding orbital, whereas \(\left.\sigma^{*}\right] \mathrm{s}\) an antibonding orbital. (3) \(\sigma 2 \mathrm{~s}\) orbital has a greater value of \(n\) that \(\sigma * 2 \mathrm{~s}\) -orbital. (4) \(\sigma 2 \mathrm{~s}\) orbital is formed only after \(\sigma \mid \mathrm{s}\).
Problem 131
\(\mathrm{N}_{2}\) and \(\mathrm{O}_{2}\) are converted into monoanions \(\mathrm{N}_{2}^{-}\) and \(\mathrm{O}_{2}^{-}\), respectively. Which of the following statements is wrong? (1) In \(\mathrm{N}_{2}, \mathrm{~N}-\mathrm{N}\) bond weakens. (2) In \(\mathrm{O}_{2}^{-}, \mathrm{O}-\mathrm{O}\) bond order increascs. (3) In \(\mathrm{O}_{2}^{-}, \mathrm{O}-\mathrm{O}\) bond order decreases. (4) \(\mathrm{N}_{2}^{-}\) becomes paramagnetic.
Problem 132
The nodal plane in the \(\pi\) -bond of ethene is located in (1) the molecular plane (2) a plane perpendicular to the molecular plane which bisects the carbon carbon sigma bond at right angle (3) a plane parallel to the molecular plane (4) a plane perpendicular to the molecular plane which contains the carbon carbon \(\sigma\) -bond
Problem 133
Anti-bonding \(\mathrm{MO}\) is formed by (1) addition of atomic orbitals (2) subtraction of atomic orbitals (3) multiplication of atomic orbitals (4) none of these
Problem 136
Ice has an open structure compared to water due to which it floats on water and occupies a greater volume of space. The open structure of ice is due to (1) solid state of ice (2) its low density (3) crystalline nature (4) hydrogen bonding
Problem 137
Which of the following statement is false? (1) The boiling point of a compound is raised by intermolecular hydrogen bonding. (2) o-nitrophenol is more volatile than p-nitrophenol because of intramolecular hydrogen bonding. (3) Lower alcohols such as methanol and ethanol arc miscible in water due to hydrogen bonding. (4) Intramolecular hydrogen bond enhances the boiling point.
Problem 140
The maximum possible number of hydrogen bonds in which a water molecule can participate is (1) 4 (2) 3 (3) 2 (4) 6
Problem 141
The false statement among the following is (1) Bond energy of covalent \(0-H\) bond in water is greater than bond energy of hydrogen bond. (2) The intermolecular attractive forces vary in the order: water \(>\) ether \(>\) alcohol. (3) The high heat of vapourisation of water is due to hydrogen bonding. (4) Acetic acid exists as a dimer in benzene due to hydrogen bonding.
Problem 142
The predominant intermolecular forces in hydrogen fluoride is due to (1) Dipole-induced dipole interaction (2) Dipole dipole interaction (3) Hydrogen bond formation (4) Dispersion interaction
