A synthesis reaction between magnesium (Mg) and oxygen (O2) might produce ____ 65. Mg2. MgCO2. a. c. b. O4. d. MgO. Which of these is a sign of a chemical reaction? ____ 66. not Heat is released A gas is off. a. c. b. A color change occurs d. Light energy is released Which statement about endothermic reactions is correct? ____ 67. a. Energy is always created in the form of c. Energy is used to electrons to heat. move to higher energy levels. b. Energy is transferred from the d. Energy is transferred from the surroundings to the reactants. reactants to the surroundings. Sugar has a lower melting point than salt because sugar is made of ____ 68. a. crystals. c. ions. molecules. atoms. b. d. A substance that undergoes a change in a chemical reaction is ____ 69. a. a product c. a reactant b. a chemical d. an enzyme A synthesis reaction is a reaction between at least two compounds in which ____ 70. a. one breaks down into at least two c. a compound burns in the presence of products. oxygen. b. a compound is decomposed by an d. a new, more complex compound is electric current. formed. How do you know that potassium, an alkali is highly reactive? ____ 71. a. It conducts heat c. It is a soft and shiny metal. b. It conducts electricity. d. It has one valence electron
____ 65. A synthesis reaction between magnesium (Mg) and oxygen (O2) might produce a. Mg2. c. MgCO2. b. O4. d. MgO. ____ 66. Which of these is not a sign of a chemical reaction? a. Heat is released c. A gas is off. b. A color change occurs d. Light energy is released ____ 67. Which statement about endothermic reactions is correct? a. Energy is always created in the form of heat. c. Energy is used to electrons to move to higher energy levels. b. Energy is transferred from the surroundings to the reactants. d. Energy is transferred from the reactants to the surroundings. ____ 68. Sugar has a lower melting point than salt because sugar is made of a. crystals. c. ions. b. molecules. d. atoms. ____ 69. A substance that undergoes a change in a chemical reaction is a. a product c. a reactant b. a chemical d. an enzyme ____ 70. A synthesis reaction is a reaction between at least two compounds in which a. one breaks down into at least two products. c. a compound burns in the presence of oxygen. b. a compound is decomposed by an electric current. d. a new, more complex compound is formed. ____ 71. How do you know that potassium, an alkali is highly reactive? a. It conducts heat c. It is a soft and shiny metal. b. It conducts electricity. d. It has one valence electron