Question

name: kara c date: unit 3 review - atoms 1. which one of the following statements is not a correct statement of the law of conservation of mass? a) matter cannot be created nor destroyed. b) the mass of a system is conserved in a chemical reaction. c) atoms are conserved in chemical reactions. d) the mass of a system is dependent upon chemical reactions that may occur. 2. hydrogen peroxide decomposes into water and oxygen when exposed to heat or light. a tightly capped bottle of hydrogen peroxide is placed on a balance and exposed to light for three weeks. the mass reading on the balance does not change. this is an example of a) the law of constant composition. b) the law of multiple proportions. c) the law of definite proportions. d) the law of conservation of mass. 3. nitrogen forms a number of different compounds with oxygen, depending upon the experimental conditions. this type of observation concerning the behavior of matter is summarized by a) the law of constant composition. b) the law of conservation of mass. c) the law of multiple proportions. d) the law of definite proportions. 4. no matter how much extra oxygen is available, 12 g of carbon always combines with 32 g of oxygen. this best illustrates the law of a) conservation of energy. b) multiple proportions. c) definite proportions. d) conservation of mass. 5. which of the following is true for normal chemical reactions as a consequence of the law of conservation of matter and energy? a) atoms can be created, destroyed, and transformed into atoms of other elements using chemical changes. b) atoms cannot be created, destroyed, nor transformed into atoms of other elements using physical or chemical means. c) atoms can be transformed into atoms of other elements by undergoing specific physical changes. d) atoms cannot be created nor destroyed, but are easily transformed into atoms of other elements. e) atoms cannot be transformed into other elements but are easily created and destroyed chemically.

Explanation:

1. The Law of Conservation of Mass states that matter is neither created nor destroyed in a chemical reaction, and the mass of a system is conserved. Option d is incorrect as it contradicts this law.
2. The mass of the hydrogen peroxide system remains the same after decomposition (even though it changes to water and oxygen), which is an example of the Law of Conservation of Mass.
3. The Law of Multiple Proportions deals with different compounds formed by the same elements in different proportions, which is the case with nitrogen and oxygen.
4. The fixed ratio of carbon to oxygen (12g : 32g) illustrates the Law of Definite Proportions.
5. According to the Law of Conservation of Matter and Energy, atoms cannot be created, destroyed, or transformed into other elements via chemical means. Physical changes (like nuclear reactions) can transform atoms, but normal chemical reactions cannot.

Answer:

1. d) The mass of a system is dependent upon chemical reactions that may occur.
2. d) the Law of Conservation of Mass.
3. c) the Law of Multiple Proportions.
4. c) Definite Proportions.
5. b) Atoms cannot be created, destroyed, nor transformed into atoms of other elements using physical or chemical means.