Explanation

Repeated extraction using portions of solvent is more efficient than using a single large portion of solvent. 

Efficiency in repeated extractions:

When you use small portions of solvent repeatedly, each extraction removes a portion of the solute from the original solution, maintaining a higher concentration gradient for subsequent extractions.

This leads to a more efficient transfer of the solute to the solvent.

Concentration gradient:

By repeatedly adding fresh solvent, you create a higher concentration difference between the solute in the original solution and the solvent, allowing for better transfer of the solute.

Single extraction limitation:

Using a single large volume of solvent may not be as efficient because the solute may not have enough time to fully transfer to the solvent due to a lower concentration gradient. 

Explanation

 One gram atom of any element refers to one mole of its atoms.

- The molar mass of chlorine (Cl) is approximately 35.5 g, so:

  - One gram atom of chlorine = 1 mole of Cl atoms = 35.5 g, not 71 g (which is for Cl₂ molecules).

Explanation

The Van der Waals constant "a" represents the magnitude of intermolecular attractions.

A higher "a" value means stronger intermolecular forces.

- He and H₂ are very light, nonpolar, and have weak intermolecular forces.

- N₂ is also nonpolar but heavier than He and H₂.

- CH₄ (Methane) is nonpolar but larger and more polarizable, so it has stronger London dispersion forces.

→ Therefore, CH₄ has the highest "a" value among the given options. 

Explanation

The fog in winter is caused by a combination of:

• Suspended water droplets (condensation)
• Dust particles in the air
• Smoke (from human activities or natural sources)

Explanation

Alkenes are a class of unsaturated hydrocarbons that contain one or more carbon-carbon double bonds (C=C).

This double bond is the defining feature of alkenes.

It makes them more reactive than saturated hydrocarbons (alkanes).

Explanation

• In the evaporation process, liquid molecules gain energy and move faster.
• It allowing them to escape from the surface of the liquid into the surrounding air.
• This occurs when the molecules have enough energy to overcome the intermolecular forces holding them to the surface.

Explanation

• Intermolecular forces are weaker than ionic or covalent bonds.
• Intermolecular forces are the attractive forces between molecules.
• While ionic and covalent bonds are the forces that hold atoms together within a molecule.

Explanation

• Synthetic resins are used in places where adhesion is required.
• They provide strong bonding properties, making them ideal for coatings, glues, and composite materials.

Explanation

• In Rutherford's famous experiment, known as the "Gold Foil Experiment" or "Rutherford's Scattering Experiment", a thin layer of zinc sulphide (ZnS) was used as the screen to detect the scattered alpha particles.
• Zinc sulphide is a phosphor that emits light when struck by radiation, allowing Rutherford to visualize the trajectory of the alpha particles.

Explanation

• Electronic configuration refers to the distribution of electrons within an atom or molecule.
• It shows how the electrons are arranged in different energy levels (shells) and sublevels (orbitals) around the nucleus.