Chemistry Practice

Two different liquids are poured together in an open container. Bubbles begin to form. After the bubbling stops, it is determined that the total weight of the two liquids is less than before they were poured together. Which best describes this observation?

• Some of the atoms during the reaction escaped into the air.

• Some of the atoms during the reaction were destroyed.

• Some of the atoms during the reaction became heavier.

• Some of the atoms during the reaction changed to a different kind of atom.

H2CO3 → H2O + CO2 How does the reaction support the Law of Conservation of Mass?

• Several molecules of water are produced.

• The mass of carbon atoms is reduced during the reaction

• The mass of the atoms in the reactant equals the mass of the atoms in the products.

• The mass of hydrogen atoms is the only thing that remains the same before and after the reaction.

Which is classified as an element?

• carbon dioxide

• iron

• vinegar

• water

Which statement is true about a chemical reaction?

• The physical states of the atoms in the reactants determine the products.

• Some of the atoms in the reactants will be a part of the products

• The number of atoms in the reactants determines the products.

• All of the atoms in the reactants will be a part of the products.

How does the concept of conservation of mass apply to chemical reactions?

• The reactants and products have exactly the same atoms.

• The reactants and products have exactly the same molecules.

• The change in the amount of matter is equal to the change in energy.

• The change in the amount of matter is only a small percentage of the total mass

Which statement best explains how the periodic table is organized?

• increasing number of neutrons from left to right

• increasing atomic number from left to right

• decreasing number of electrons from left to righ

• decreasing atomic mass number from left to right

How does a balanced chemical equation satisfy the Law of Conservation of Mass?

• During a chemical reaction, matter is destroyed.

• During a chemical reaction, one or more new substances are formed.

• During a chemical reaction, the total number of atoms increases.

• During a chemical reaction, the total amount of matter stays the same.

Which is true of a chemical equation?

• Products and reactants must be balanced.

• Subscripts must be used with all products and reactants.

• Energy must be included in the beginning of the reaction.

• Coefficients must be used with all products and reactants.

Max combines baking soda and vinegar in a flask. Which is the most likely reason Max should place a balloon over the mouth of the flask before he mixes the two substances?

• to prevent any liquid used as a reactant from escaping during the reaction

• to prevent any powder used as a reactant from escaping during the reaction

• to prevent any gas formed as a product from escaping during the reaction

• to prevent any liquid formed as a product from escaping during the reaction

Which best describes elements found in a column of the periodic table?

• The elements have the same-size atoms.

• The elements have the same atomic number.

• The elements have similar chemical properties.

• The elements are all found naturally in the same physical state.