One of your classmates is having trouble understanding ions, he explain the formation of a cation like this: "when you add an electrons, you get a positive charge because adding is positive in math

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.

i think it is true since you can test the answer and can use observations to complete it.