The scientist who discovered the relationship between the relative volume of a gas and the stoichiometric coefficients in a chemical equation was .

The scientist who discovered the relationship between the relative volume of a gas and the stoichiometric coefficients in a chemical equation was Gay-Lussac

Explanation:

Gay -Lussac was a french chemist he proposed 2 fundamental laws of gases in 19th century.

He studied the  relationship between the pressure of a gas and its absolute temperature.

Gay-Lussac's Law states that the pressure of a given mass of gas varies directly with the absolute temperature of the gas, when the volume is kept constant.

explanation:

venn diagram is pictorial representation with of circles showing the relation between two finite sets or things. the intersection part of two circles conveys the relation present in between those sets or things.

here in the venn diagram of sand and salt two circles represent sand and salt. but the area falling under the intersection of these circle represents the mixture of sand and salt.

so, in a venn diagram the mixture will be placed in a middle that is in between the intersection of two circles.