Questions

Semiconductors are those materials that are neither good conductors nor the good insulators of heat and electricity. Silicon (Si), Germanium (Ge) and Cadmium Sulphide (CdS) are semiconductors which work as conductors in some special conditions only.

The processes both osmosis and diffusion come under passive transport and require no energy. The movement of solute from the region of higher concentration to the region of lower concentration is nothing but diffusion.

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Foreign keys are the columns of a table that points to the primary key of another table. They act as a cross-reference between tables.

In detail : A Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. In simpler words, the foreign key is defined in a second table, but it refers to the primary key or a unique key in the first table.