1. Distinguish between a mixture and a pure substance. ​

Mixture - A mixture is a substance which consist of two or more elements or compounds not chemically combined together.

Pure Substance - A pure substance is a substance which has only one type of atoms or molecules thereby having a constant composition and structure.

1)Mixture is the combination of substance

2)There are two types of mixture such as heterogeneous mixture and homogeneous mixture

3)foreg=Salt solution ,sedimentation

Pure substance

1)Pure substances are also called elements

2)They are made up of small atoms

3)for eg= oxygen,Venadium ,Iron,Oxygen

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.