Name the law in Physics which states that equal volume of all gases under the same conditions of temperature and pressure contain equal number of molecules.

Avogadro’s Law

The correct answer is option 3. Avogadro’s Law.

The law in physics which states that equal volumes of all gases under the same conditions of temperature and pressure contain equal numbers of molecules is Avogadro’s Law.

Avogadro's Law states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. It implies that the number of molecules in a gas is directly proportional to its volume, assuming constant temperature and pressure. This law is named after Amedeo Avogadro, an Italian scientist who first proposed it in the early 19th century.