Melting And Boiling Point

The boiling point of a compound depends on factors such as molecular weight, polarity, and the presence of halogen atoms. In general, the boiling point increases with increasing molecular weight and polarizability.

Let's analyze the given compounds:

• CH₃Cl: Methyl chloride is a small molecule with one chlorine atom, resulting in a relatively low boiling point.
• CH₃Br: Methyl bromide contains a larger bromine atom, leading to stronger van der Waals forces and a slightly higher boiling point than CH₃Cl.
• CH₂Br₂: Dibromomethane has two bromine atoms, increasing its molecular weight and boiling point further.
• CHBr₃: Tribromomethane has three bromine atoms, making it the heaviest and most polarizable of the series, with the highest boiling point.

Therefore, the increasing order of boiling points is:

CH₃Cl < CH₃Br < CH₂Br₂ < CHBr₃

Correct Answer:

Correct Answer: (B) CH₃Cl < CH₃Br < CH₂Br₂ < CHBr₃

Boiling Point Elevation

Given:

• Boiling point of water at hill station = 98.98°C
• Desired boiling point = 100°C
• Elevation in boiling point,
• Molal elevation constant,
• Mass of water = 2 kg
• Molar mass of urea = 60 g/mol

Using the formula:

Where is molality = moles of solute / kg of solvent

So,

Since water is 2 kg:

Correct Answer: 240 g

The metal with the highest melting point in the first series of transition elements is chromium.

Explanation:

In the first series of transition elements (Scandium to Zinc), chromium has the highest melting point, which is due to its unique electron configuration. Chromium exhibits a more stable configuration in its crystalline structure, leading to stronger metallic bonds. This, in turn, results in a higher melting point compared to other elements in the series.