Regents Chemistry Test Preparation Practice

    Classification Of Matter


    Base your answers to questions 12 on the information below.

    Nitrogen gas and oxygen gas make up about 99% of Earth’s atmosphere. Other atmospheric gases include argon, carbon dioxide, methane, ozone, hydrogen, etc.

    The amount of carbon dioxide in the atmosphere can vary. Data for the concentration of CO2(g) from 1960 to 2000 are shown in the table below.

    identification-of-element fig: chem12013-exam_g19.png


    Base your answers to questions 13 on the information below and on your knowledge of chemistry.

    In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al2O3(ℓ) extracted from bauxite is dissolved in Na3AlF6(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are carbon dioxide and molten aluminum metal.

    classification-of-matter fig: chem62013-exam_g18.png


    Base your answers to questions 14 on the information below.

    John Dalton, an early scientist, sketched the structure of compounds using his own symbols for the elements known at the time. Dalton’s symbols for four elements and his drawing of potassium aluminum sulfate are represented by the diagram below.

    bonding-tendency-of-elements fig: chem62012-exam_g22.png

    Today, it is known that the chemical formula for potassium aluminum sulfate is KAl(SO4)2•12H2O. It is a hydrated compound because water molecules are included within its crystal structure. There are 12 moles of H2O for every 1 mole of KAl(SO4)2. The compound contains two different positive ions. The gram-formula mass of KAl(SO4)2•12H2O is 474 grams per mole.


    Base your answers to questions 15 on the information below.

    Iron has been used for thousands of years. In the air, iron corrodes. One reaction for the corrosion of iron is represented by the balanced equation below.

    Equation 1: 4Fe(s) + 3O2(g) → 2Fe2O3(s)

    In the presence of water, iron corrodes more quickly. This corrosion is represented by the unbalanced equation below.

    Equation 2: Fe(s) + O2(g) + H2O(ℓ) → Fe(OH)2(s)