Question

According to Avogadro’s hypothesis, an equal volume of gases under the same condition of temperature and pressure will contain:
(a)- The same number of molecules
(b)- Different number of molecules
(c)- The same number of molecules only if their molecular masses are equal
(d)- The same number of molecules if their densities are equal

Answer 1

Hint: Berzelius was a Swedish chemist. He tried to correlate with Dalton’s Atomic theory and Gay-Lussac’s law of gaseous volumes. So, his result was contrary to the Modified Dalton’s Atomic Theory.

Complete step by step answer:
John Dalton in 1808, gave his theory when he studied elements, compounds, mixtures, and laws of chemical combination. This theory was Dalton's atomic theory. So major points or postulates of this theory are as follows:
The matter is made up of very small particles called atoms and these atoms are indivisible.
All the atoms in the same element are identical, or we can say that they have the same size, shape, and weight.
Different elements have different chemical properties because they have different atoms and so on.
 Combining of atoms of the same or different elements leads to the formation of molecules.
 Compounds are formed when atoms combine and they have a simple ratio.
Atoms combine in a different ratio to form more than one type of compound.
The smallest particle which takes place in a chemical reaction is an atom.
Atoms can neither be created nor destroyed.
This theory had some limitations, so the modified Dalton’s Atomic theory formed. It states that:
Atoms are divisible into many particles, most important of them are protons, electrons, and neutrons.
The atoms have isobars and isotopes.
The ratios of combining molecules can be simple but not always.
Atoms are no longer considered as indestructible.
So, Berzelius argued that while electrons combine in a simple ratio by atoms, gases combine in a simple ratio by volume. According to Berzelius Hypothesis- "Equal volumes of all gases under similar conditions of temperature and pressure contain an equal number of atoms”.
But Avogadro made a hypothesis that clearly distinguished between the two ultimate particles of matter, i.e., atoms and molecules. His hypothesis states that "Equal volumes of all gases under similar conditions of temperature and pressure contain an equal number of molecules".
So, the correct answer is “Option A”.

Note: The law of gaseous volume states that: Under similar conditions of temperature and pressure when gases combine in volumes they bear a simple ratio to one another and the volume of the product.