which of the following compounds is ionic

HESI A2

Chemistry Hesi A2

1. Which of the following compounds is ionic?

A. NaCl
B. H₂O
C. HCl
D. NH₃

Correct answer: A

Rationale: The correct answer is NaCl (sodium chloride). Ionic compounds are formed by the transfer of electrons between a metal and a nonmetal. In NaCl, sodium (Na) is a metal, and chlorine (Cl) is a nonmetal. Sodium donates an electron to chlorine, leading to the formation of the ionic bond between them. This results in the formation of an ionic compound, where positively charged sodium ions are attracted to negatively charged chloride ions, creating a crystal lattice structure. Choices B, C, and D are not ionic compounds. H₂O (water) is a covalent compound formed by the sharing of electrons between two nonmetals (oxygen and hydrogen). HCl (hydrogen chloride) and NH₃ (ammonia) are also covalent compounds involving nonmetals sharing electrons, not transferring them.

2. How many grams are in 6 kilograms?

A. 600 grams
B. 6000 grams
C. 600 grams
D. 60,000 grams

Correct answer: B

Rationale: There are 1,000 grams in a kilogram. Therefore, to convert kilograms to grams, you need to multiply the number of kilograms by 1,000. In this case, 6 kilograms would be equal to 6 × 1,000 = 6,000 grams. Choices A, C, and D are incorrect because they do not apply the correct conversion factor from kilograms to grams.

3. Solve for x: 2x - 7 = 9.

A. x = 10
B. x = 7
C. x = 8
D. x = 5

Correct answer: C

Rationale: To solve the equation 2x - 7 = 9, first, add 7 to both sides to isolate the variable: 2x = 16. Then, divide by 2 to solve for x: x = 8. Choice A (x = 10) is incorrect because the solution is x = 8, not 10. Choice B (x = 7) is incorrect as it does not correctly solve the equation. Choice D (x = 5) is incorrect as it does not yield the correct solution for x.

4. Which hormone is released by the posterior pituitary gland?

A. Oxytocin
B. Thyroxine
C. Insulin
D. ADH

Correct answer: A

Rationale: Oxytocin is the correct answer. It is released by the posterior pituitary gland and plays a vital role in childbirth and lactation. Oxytocin promotes uterine contractions during labor and milk ejection during breastfeeding. Choice B, Thyroxine, is incorrect as it is produced by the thyroid gland. Choice C, Insulin, is incorrect as it is produced by the pancreas. Choice D, ADH (Antidiuretic Hormone), is also released by the posterior pituitary gland, but it is not the hormone primarily associated with childbirth and lactation.

5. Another word for UNDER OBSERVATION is?

A. Cognition
B. Isolation
C. Surveillance
D. Assessment

Correct answer: C

Rationale: Another word for UNDER OBSERVATION is surveillance. Surveillance refers to the close observation of a person, group, or place, especially in a secret or discreet manner. It involves monitoring and watching over someone or something closely for a specific purpose. Therefore, the word 'surveillance' is the most suitable synonym for under observation in this context. Choice A, 'Cognition,' refers to the mental process of acquiring knowledge and understanding through thoughts, experience, and the senses; it is not synonymous with under observation. Choice B, 'Isolation,' means the process or fact of isolating or being isolated, which does not convey the idea of close monitoring. Choice D, 'Assessment,' involves evaluating or judging the nature, ability, or quality of something, which is different from the act of observing closely.