Nursing Elites

1. What is the correct formula for sodium nitrate?

• A. NaNO
• B. Na NO
• C. NaNO₃
• D. Na NOâ‚‚

Correct answer: C

Rationale: The correct formula for sodium nitrate is NaNO₃. In this formula, 'Na' represents sodium, 'N' represents nitrogen, and 'O₃' represents three oxygen atoms. Sodium nitrate consists of one sodium ion (Na⁺) and one nitrate ion (NO₃⁻), which means the correct formula is NaNO₃. Choice A (NaNO) is incorrect as it lacks the subscript indicating the presence of three oxygen atoms. Choice B (Na NO) is incorrect as it includes a space between 'Na' and 'NO', which is not part of the standard chemical formula notation. Choice D (Na NO₂) is incorrect as it indicates a different compound with a nitrite ion (NO₂⁻) instead of nitrate ion.

2. What is the name of the negatively charged subatomic particles?

• A. Protons
• B. Neutrons
• C. Electrons
• D. Isotopes

Correct answer: C

Rationale: The correct answer is C: Electrons. Electrons are the negatively charged subatomic particles. They are found outside the atomic nucleus and carry a negative charge. Protons are positively charged particles found in the nucleus, neutrons have no charge, and isotopes are atoms of the same element with different numbers of neutrons, not subatomic particles.

3. Cobalt-60 has a half-life of 5 years. If you start with 20 g of cobalt-60, how much is left after 10 years?

• A. 15 g
• B. 10 g
• C. 5 g
• D. 2.5 g

Correct answer: C

Rationale: Cobalt-60's half-life of 5 years means that after 5 years, half of the initial amount remains. Therefore, after 10 years, a quarter (half of a half) of the initial amount will remain. Starting with 20 g, after 10 years, 5 g of cobalt-60 will be left. Choice A (15 g) is incorrect because it assumes a linear decrease, not considering the exponential decay characteristic of radioactive substances. Choice B (10 g) is incorrect as it overlooks that after 10 years, more decay has occurred. Choice D (2.5 g) is incorrect as it represents only an eighth of the initial amount after 10 years, not a quarter.

4. When an acid is added to a base, water and a salt form. What kinds of bonds form in these two compounds?

• A. Liquid and metallic
• B. Polar and nonpolar covalent
• C. Polar covalent and ionic
• D. Ionic only

Correct answer: C

Rationale: In water, the bond formed between the oxygen atom and the hydrogen atoms is a polar covalent bond. The oxygen atom attracts the shared electrons more strongly, creating a partial negative charge on the oxygen and a partial positive charge on the hydrogen atoms. In the salt formed, the bond between the metal cation and the nonmetal anion is predominantly an ionic bond. The metal cation donates electrons to the nonmetal anion, resulting in the formation of oppositely charged ions that are held together by electrostatic attractions. Choices A and B are incorrect because water and salts do not form bonds that are liquid and metallic, or polar and nonpolar covalent. Choice D is incorrect as it oversimplifies the types of bonds present in water and salts, failing to differentiate between the covalent bond in water and the ionic bond in the salt.

5. What charge do Group VA elements typically have?

• A. -1
• B. -2
• C. -3
• D. 0

Correct answer: C

Rationale: Group VA elements, also known as Group 15 elements, typically have a charge of -3. This is because they have five valence electrons and tend to gain three electrons to achieve a stable octet configuration, resulting in a -3 charge. Choice A (-1) and Choice B (-2) are incorrect because Group VA elements need to gain three electrons to reach a stable electron configuration, not just one or two. Choice D (0) is also incorrect because Group VA elements do not lose electrons to form a charge of 0.

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