Explanation

F-block elements are also known as inner transition elements.

They include the lanthanides and actinides and are located at the bottom of the periodic table, separated into two rows.

This placement is due to their electron configuration, where the "n-2" f orbitals are being filled.

Explanation

The biosphere includes all of these: the Atmosphere, the Hydrosphere, and the Lithosphere.

The biosphere is the zone on Earth where life exists, encompassing the living organisms and their interactions with the surrounding environment, including the atmosphere, hydrosphere (water bodies), and lithosphere (land).

Explanation

Vacuum distillation is used to distill substances at lower temperatures by reducing the pressure, which lowers the boiling point of the substances.

Explanation

The comparative rates at which solutes move in paper chromatography depend on Rf values. 

Rf values (retention factors) represent the ratio of the distance traveled by a solute to the distance traveled by the solvent front on the paper.

Since different solutes have different polarities and affinities for the mobile and stationary phases, they will travel at different speeds, resulting in unique Rf values.

Therefore, the comparative movement of solutes is directly related to their Rf values. 

Explanation

Explanation

Leukemia is a cancer of the body's blood-forming tissues.

Including the bone marrow and the lymphatic system.

Some forms of leukemia are more common in children.

Explanation

Explanation

The yellowing of leaves due to lack of chlorophyll is called chlorosis.

This condition occurs when the green pigment, chlorophyll, is reduced or absent in the leaves, causing them to turn yellow. 

Explanation

"Minutes ago" indicates a completed action in the past, so simple past tense is used.

Correct sentence: "He went out five minutes ago."

Explanation

Chronology means تاریخ

Time sequence means وقت کی ترتیب