Mole | MCQs

Explanation

To find the moles, divide the mass of NaOH (60g) by its molar mass (40g/mol). 

Moles = 60/40 =1.5 moles

Explanation

The carbon-carbon (C-C) bond length in benzene is 1.39 Å (angstroms).

This bond length is intermediate between a single bond (typically around 1.54 Å) and a double bond (typically around 1.34 Å) due to the resonance structure of benzene

Where the electrons are delocalized over the six carbon atoms.

This delocalization results in a uniform bond length throughout the benzene ring.

Explanation

SF₆ is stable although the central S atom expands its octet and has 12 electrons in the outermost shell.

This is because the central S atom forms 6 S-F bonds with 6 F atoms, and S-F bond is a very strong covalent bond.

The molecule is stabilized by the 6 strong S-F bonds.

Explanation

Remember that water has 2 lone pairs on oxygen.

Hence, according to VSEPR theory, the water molecule arrives at a bent or a V-shape

Due to the presence of lone pair-lone pair, lone pair-bond pair and bond pair-bond pair repulsions

Explanation

• Lone pairs are pairs of outer shell electrons that are not used in bonding. They are also known as non-bonding pairs or unshared pairs.
• These electrons are typically found in the outermost energy level (valence shell) of an atom and are not involved in forming chemical bonds with other atoms.

Explanation

• Dry ice is the solid form of carbon dioxide (CO2), and it is an example of a molecular crystal.
• In a molecular crystal, the molecules are held together by weak intermolecular forces such as van der Waals forces or hydrogen bonds, rather than by strong chemical bonds.

Explanation

The molecular Geometry of SF6 (sulfur hexafluoride) is octahedral. 

In this molecule, the central atom i.e. sulphur has a total of six electrons in its valence shell

And in the molecule, we have six fluorine atoms so it shares one electron with each fluorine atom.

So this molecule has six bond pairs and no lone pair.

So its structure is octahedral

The bond angles in sulfur hexafluoride molecules are 90A∘ and 180A∘.

Explanation

In forming H2CO3 (carbonic acid), each oxygen atom utilizes sp2 hybrid orbitals.

Explanation

Elements having zero nuclear spin cannot be directly determined by NMR (Nuclear Magnetic Resonance) spectroscopy because NMR relies on the detection of signals from nuclei with non-zero nuclear spin.

Explanation

The value of the molar extinction coefficient of compound Z is 150 mol-1 dm3 cm-1.