Mole | MCQs

Explanation

A covalent bond forms when two non-metals share electrons.

This type of bond results in the formation of molecules like H₂O and CO₂.

Explanation

Step 1: Calculate the molar mass of S8

The atomic mass of sulfur (S) is approximately 32 g/mol. The molar mass of S8 = 8 * 32 = 256 g/mol.

Step 2: Calculate the number of moles of S8

Number of moles = mass of S8 / molar mass of S8 = 64 g / 256 g/mol = 0.25 mol.

Step 3: Calculate the number of molecules of S8

Number of molecules = number of moles * Avogadro's number (NA) = 0.25 * NA.

Step 4: Calculate the number of sulfur atoms

Each molecule of S8 contains 8 sulfur atoms. Therefore, the total number of sulfur atoms = 8 * number of molecules = 8 * 0.25 * NA = 2 * NA = 2NA.

Explanation

Molar mass of CO₂ = 12 (C) + 16×2 (O) = 44 g/mol

Number of moles = Mass / Molar mass = 60 / 44 ≈ 1.364 mol

Explanation

BF₃ (Boron trifluoride) is an electron-deficient molecule because boron has only 6 valence electrons after bonding, which is less than the stable octet.

It tends to accept a lone pair from other atoms to complete its octet, making it a Lewis acid.

Explanation

Explanation

According to Valence Shell Electron Pair Repulsion (VSEPR) theory, XeF₄ (xenon tetrafluoride) has a square planar geometry.

Xenon in XeF₄ has six electron pairs around it: four bonding pairs and two lone pairs.

Explanation

A probe is a short, single-stranded DNA or RNA sequence that binds to a complementary gene of interest.

It is used to screen genomic libraries for specific genes.

Explanation

The nucleus is the control center of the cell, regulating all cellular activities, including growth and reproduction.

It contains the cell’s genetic material (DNA).

Explanation

• An atom is the smallest particle of an element that retains the properties of that element.
• It is the smallest unit of a chemical element, and it cannot be broken down into smaller particles.

Explanation