Nursing Elites

1. Which type of bond is exemplified by KCl?

• A. Ionic bond
• B. Covalent bond
• C. Hydrogen bond
• D. Polar covalent bond

Correct answer: A

Rationale: KCl exemplifies an ionic bond. In an ionic bond, electrons are transferred between atoms, resulting in the formation of ions. In the case of KCl, potassium (K) donates an electron to chlorine (Cl), leading to the creation of K+ and Cl- ions, which are held together by electrostatic forces of attraction. Choice B, covalent bond, is incorrect because covalent bonds involve the sharing of electrons between atoms, not the transfer of electrons as seen in KCl. Choice C, hydrogen bond, is incorrect as hydrogen bonds are a type of intermolecular force, not a bond formed by the transfer or sharing of electrons between atoms. Choice D, polar covalent bond, is also incorrect because although it involves the sharing of electrons with an unequal distribution of charge, KCl is a clear example of ionic bonding where electrons are completely transferred.

2. When is a solution formed?

• A. One substance dissolves in another
• B. Two or more substances react chemically
• C. A solid changes to a liquid
• D. None of the above

Correct answer: A

Rationale: A solution is formed when one substance dissolves in another. This process creates a homogeneous mixture where the solute is dispersed in the solvent, resulting in a uniform composition throughout the mixture. Choice B is incorrect because chemical reactions involve the transformation of substances into new compounds, not the formation of solutions. Choice C is incorrect as it describes a physical change from a solid to a liquid, not the formation of a solution. Choice D is incorrect as one substance dissolving in another is the defining characteristic of a solution.

3. An object is thrown upwards and reaches a maximum height. Which of the following statements is TRUE about its velocity and acceleration at the peak?

• A. Velocity is zero and acceleration is maximum upwards.
• B. Velocity is maximum and acceleration is zero.
• C. Velocity is maximum and acceleration is maximum upwards.
• D. Velocity is zero and acceleration is maximum downwards.

Correct answer: A

Rationale: At the peak of the object's motion, its velocity is zero because it momentarily stops before changing direction and starts to fall back down. The acceleration at the peak is maximum upwards as gravity is acting against the object's motion, slowing it down until it stops momentarily. Choice A is correct because at the peak, the object's velocity is zero, and the acceleration is maximum upwards. Choice B is incorrect because the velocity is not maximum but zero at the peak. Choice C is incorrect as both velocity and acceleration are not maximum at the peak. Choice D is incorrect as the acceleration at the peak is upwards, opposing the object's motion, not downwards.

4. Which of the following infectious diseases can be caused by a protozoan parasite?

• A. Measles
• B. Malaria
• C. Mumps
• D. Mononucleosis

Correct answer: B

Rationale: The correct answer is B: Malaria. Malaria is caused by Plasmodium, a protozoan parasite transmitted through the bite of infected mosquitoes. Measles and mumps are viral diseases caused by separate viruses. Mononucleosis, on the other hand, is caused by the Epstein-Barr virus, which is also a viral infection. Therefore, choices A, C, and D are incorrect as they are caused by viruses, not protozoa.

5. Which of the following components is found in DNA?

• A. Uracil
• B. Deoxyribose
• C. Guanine
• D. Phosphate group

Correct answer: B

Rationale: The correct answer is B: Deoxyribose. DNA is composed of nucleotides containing deoxyribose sugar, phosphate group, and nitrogenous bases (adenine, thymine, guanine, and cytosine). Deoxyribose is the sugar component specific to DNA, while ribose is found in RNA. Guanine (choice C) is a nitrogenous base present in both DNA and RNA. Uracil (choice A) is a nitrogenous base specific to RNA, replacing thymine found in DNA. The phosphate group (choice D) is an essential part of nucleotides in both DNA and RNA, providing the backbone structure for the nucleic acid chains.

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