Question

Which of the following statements about Avogadro’s hypothesis is correct?
A.Under similar conditions of temperature and pressure gases react with each other in simple ratios.
B.Under similar conditions of temperature and pressure, equal volumes of all gases contain the same number of molecules.
C.At $NTP$ all gases contain the same number of molecules.
D.Gases always react with gases only at the given temperature and pressure.

Answer 1

Hint: Consider all the options by Avogadro’s hypothesis which states that when there is equal volume of gases under the same condition of temperature and pressure should have equal number of molecules, we can classify our answer.

Complete answer:
As many scientists have given their proposal on Laws of chemical combination so here we have Lorenzo Romano Amedeo Carlo Avogadro di Quareqa edi Carreto very big name right so he has also given his law which we know now as Avogadro Law in$1811$, in which he state that under when there is equal volume of gases under the same condition of temperature and pressure should have equal number of molecules And he also made a distinction between atoms and molecules which now in present time is quite understandable, so from the above option we have one similar ones which state that ‘Under similar conditions of temperature and pressure, equal volumes of all gases contain same number of molecules’.
Whereas in our first option which states that ‘Under similar conditions of temperature and pressure gases react with each other in simple ratio’ which is not correct according to Avogadro Law.

Now if we see our third option which states that ‘At $NTP$ all gases contain the same number of molecules’ which is false as when we will calculate for any two gases and calculate the number of molecules at $NTP$ it is not going to be equal.

Now let’s proceed to our last option which states that ‘Gases always react with gases only at the given temperature and pressure’ which is also a little bit similar to the first option so we can say that this statement is not correct.

Note:
At that time when Avogadro propose his law with an example that $2$ volume hydrogen react with $1$ volume of oxygen to give $2$ volume of water vapour which Dalton and others believed that atoms of the same kind cannot combine and molecules of oxygen and hydrogen containing two atoms did not exist but as we know it do exist.