(A) if both sentences are true, (B) if both sentences are false, (C) if the first sentence is true but the second is false, and (D) if the first sentence is false but the second is true. 1. Radioactive elements gain stability by single emission, and a successive emission creates a series. Half-life is the half of the amount of life that a radioactive material will continue to exist before it decays completely. 2. When water is mixed with metals, a metal hydroxide is formed and oxygen gas is evolved. The evolution of the oxygen gas from the reaction of metals and water is indicated by the hastened consumption of the splinter. 3. When water is mixed with sodium carbonate, a weak base will be formed. When water is mixed with sodium chloride, a weak base will be formed. 4.  In the Winkler Titration Method, sodium thiosulfate is standardized against a known concentration of magnesium iodate. The normality (N) of a solution is always equal to its molarity (M). 5. Dissolved oxygen (DO) refers to the level of free, non-compound oxygen present in water or other liquids. DO is an important parameter in assessing water quality because of its influence on the organisms living within a body of water.

(A) if both sentences are true,
(B) if both sentences are false,
(C) if the first sentence is true but the second is false, and
(D) if the first sentence is false but the second is true.

1. Radioactive elements gain stability by single emission, and a successive emission creates a series. Half-life is the half of the amount of life that a radioactive material will continue to exist before it decays completely.

2. When water is mixed with metals, a metal hydroxide is formed and oxygen gas is evolved. The evolution of the oxygen gas from the reaction of metals and water is indicated by the hastened consumption of the splinter.

3. When water is mixed with sodium carbonate, a weak base will be formed. When water is mixed with sodium chloride, a weak base will be formed.

4.  In the Winkler Titration Method, sodium thiosulfate is standardized against a known concentration of magnesium iodate. The normality (N) of a solution is always equal to its molarity (M).

5. Dissolved oxygen (DO) refers to the level of free, non-compound oxygen present in water or other liquids. DO is an important parameter in assessing water quality because of its influence on the organisms living within a body of water.