MATHES WYTOPP SCIENCE REVIEW

Which statement best describes the law of conservation of mass?

• Mass is neither created nor destroyed in a chemical reaction.
• Mass can be converted into energy.
• The mass of products in a chemical reaction is greater than the mass of the reactants.
• The mass of reactants in a chemical reaction is always equal to the mass of the products.

What is an element?

• A substance that can be broken down into simpler substances by chemical reactions.
• A compound made up of two or more different elements.
• A pure substance that cannot be broken down into simpler substances by chemical reactions.
• A mixture of two or more substances that are not chemically combined.

What is a chemical reaction?

• The process by which atomic nuclei are split or combined.
• The process that changes one or more substances into one or more new substances.
• The process of a substance changing from one phase to another.
• The process of mixing two substances to form a solution.

Which of the following is a sign of a chemical change?

• Boiling water
• Dissolving sugar in water
• Rusting of iron
• Melting ice

What is the purpose of a catalyst in a chemical reaction?

• To increase the yield of the product
• To decrease the reaction temperature
• To speed up the reaction without being consumed
• To act as a reactant in the reaction

Which of the following is an example of a chemical property?

• Density
• Solubility
• Reactivity with acid
• Melting point

In a balanced chemical equation, why must the number of atoms for each element be the same on both sides of the equation?

• To satisfy the law of conservation of mass
• To ensure that the reaction is exothermic
• To ensure that the reaction is endothermic
• To increase the rate of the reaction

What information does a chemical formula provide?

• The physical state of a compound
• The elements present and the ratios of their atoms
• The temperature at which a reaction occurs
• The speed at which a chemical reaction occurs

Which type of bond is formed by the sharing of electrons between atoms?

• Ionic bond
• Covalent bond
• Metallic bond
• Hydrogen bond

Which statement best describes an exothermic reaction?

• The reaction absorbs heat from the surroundings.
• The reaction releases heat to the surroundings.
• The reaction occurs spontaneously.
• The reaction requires energy to proceed.