Which of these is an example of a physical change?
A) iron melting
B) steel rusting
C) paper burning
D) wood decaying

A physical change changes the state on object is in, making the answer A) iron melting. Since it's melting, it's going from solid to liquid.

- decrease the number of plants and animals living in the water.

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.