10ee Chem -2

Which observation does NOT indicate that a chemical reaction has occurred?

• formation of a precipitate

• production of a gas

• evolution of heat and light

• change in total mass of substances

A solid produced by a chemical reaction in solution that separates from the solution is called

• a precipitate

• a reactant

• a molecule

• the mass of a product

In writing an equation that produces hydrogen gas, the correct representation of hydrogen gas is

• H

• 2H

• H₂

• OH

What is the small whole number that appears in front of a formula in a chemical equation?

• a subscript

• a superscript

• a ratio

• a coefficient

To balance a chemical equation, it may be necessary to adjust the

• coefficients

• subscripts

• formulas of the products

• number of products

According to the law of conservation of mass, the total mass of the reacting substances is

• always more than the total mass of the products

• always less than the total mass of the products

• sometimes more and sometimes less than the total mass of the products

• always equal to the total mass of the products

In an equation, the symbol for a substance in water solution is followed by

• (l)

• (g)

• (aq)

• (s)

When the equation Fe₃O₄ + Al ---> Al₂O₃ + Fe is correctly balanced, what is the coefficient of Fe?

• 3

• 4

• 6

• 9

Which of the following is a formula equation for the formation of carbon dioxide from carbon and oxygen?

• Carbon plus oxygen yields carbon dioxide

• C + O₂ ---> CO₂

• CO₂ ---> C + O₂

• 2C + O --->CO₂

For the formula equation 2Mg + O₂ ---> 2MgO, the word equation would begin

• Manganese plus oxygen . . . .

• Molybdenum plus oxygen . . . .

• Magnesium plus oxygen . . . .

• Heat plus oxygen