Which sample of matter is a mixture?

NYC Chemistry Regents Exam Jan 2023

Which sample of matter is a mixture? (1) CO2 (g) (2) CCl4(l)

(3) MgCl2 (aq)

(4) Sn(s)

Solution: A mixture is composed of two or more substances (elements or compounds). Aq stands for aqueous which means dissolved in water. MgCl2 (aq) is a mixture because it is composed of MgCl2 and H2O. Any substance dissolved in water is a homogeneous mixture.