Nokea
Why are elements in Group 18 (Noble gases) generally unreactive?
- A. They have high atomic masses
- B. They lack valence electrons
- C. Their outermost electron shells are completely filled
- D. They exist as single atoms, not molecules
Correct Answer: C
Rationale: Elements in Group 18 (Noble gases) are generally unreactive because their outermost electron shells are completely filled. This results in high stability and low reactivity since they have achieved a full valence shell configuration, making them less likely to gain, lose, or share electrons with other atoms. The full valence shell configuration leads to a minimal tendency for these elements to form chemical bonds, hence exhibiting low reactivity. Choices A, B, and D are incorrect because high atomic masses, lack of valence electrons, and existing as single atoms do not directly contribute to the unreactivity of noble gases. It is the full valence shell configuration that is the primary reason for their inert nature.
You may also like to solve these questions
What is the technical term for the involuntary muscular contractions that move food through the digestive tract?
- A. Segmentation
- B. Peristalsis
- C. Chylification
- D. Emulsification
Correct Answer: B
Rationale: Peristalsis is the term used to describe the involuntary muscular contractions that move food through the digestive tract. This process involves rhythmic contractions and relaxations of the muscles in the digestive system, which help propel food from the esophagus to the stomach and through the intestines for digestion and absorption of nutrients. Segmentation refers to the mixing movements in the intestines that aid in the absorption of nutrients but is not the term for the movement of food through the digestive tract. Chylification is not a recognized term in digestive physiology. Emulsification is the process of breaking down fat globules into smaller droplets to aid in digestion, not the movement of food through the digestive tract.
Which of the following terms refers to a muscle that lengthens while another muscle contracts to produce movement?
- A. Synergist
- B. Agonist
- C. Antagonist
- D. Flexor
Correct Answer: C
Rationale: The correct answer is 'Antagonist.' An antagonist muscle is a muscle that lengthens while another muscle (agonist) contracts to produce movement. The antagonist muscle relaxes to allow the agonist muscle to contract effectively. In this scenario, the antagonist muscle works in opposition to the agonist muscle, providing control and precision to movement. The other choices are incorrect because a synergist muscle assists the agonist muscle in performing a movement, an agonist muscle is the primary muscle responsible for generating movement, and a flexor muscle is a muscle that decreases the angle at a joint.
Ectopic pregnancy is a serious condition that occurs when a fertilized egg implants outside the uterus. What is the most common location for an ectopic pregnancy?
- A. Ovary
- B. Fallopian tube
- C. Cervix
- D. Vagina
Correct Answer: B
Rationale: The most common location for an ectopic pregnancy is the fallopian tube. This occurs when the fertilized egg implants and grows outside the uterus, typically in the fallopian tube. Ectopic pregnancies in other locations such as the ovary, cervix, or vagina are much rarer. The fallopian tube is the correct answer because it is the site where the fertilized egg may get stuck during its journey to the uterus, leading to implantation and growth outside the uterus. The ovary is not a common site for ectopic pregnancy, and implantation there can be life-threatening due to the risk of severe bleeding. The cervix and vagina are not typical sites for implantation of a fertilized egg, making them less likely locations for an ectopic pregnancy.
What is the science of classifying organisms into different groups based on their evolutionary relationships called?
- A. Taxonomy
- B. Microbiology
- C. Genetics
- D. Epidemiology
Correct Answer: A
Rationale: Taxonomy is the science of classifying organisms into different groups based on their evolutionary relationships. It involves identifying, naming, and categorizing living organisms according to their similarities and differences, helping us understand the diversity of life. Microbiology (option B) focuses on the study of microorganisms. Genetics (option C) deals with genes and heredity. Epidemiology (option D) explores the distribution and determinants of health-related states or events in populations. Therefore, the correct answer is Taxonomy as it specifically pertains to the classification of organisms based on their evolutionary relationships.
When is work done by a force on an object?
- A. Only when the object moves in the direction of the force
- B. Only when the object moves against the force
- C. Only when the object moves vertically
- D. Only when the force is applied for a specific duration
Correct Answer: A
Rationale: Work is done by a force on an object when the object moves in the direction of the force. This is because work is defined as the product of the force applied to an object and the distance over which the force is applied. When the object moves in the direction of the force, the force contributes to the displacement of the object, resulting in work being done. If the object moves perpendicular to the force, no work is done because the force does not contribute to the displacement. Moving against the force also results in work being done as the force is causing the displacement. The vertical movement of the object does not determine whether work is done; it is the alignment of the force with the object's displacement that matters. The duration of force application does not impact whether work is done; as long as the force causes the object to move in its direction, work is being done.