1.
An alternating-current-carrying wire induces a current in another nearby wire. This phenomenon is the basis of operation of which of the following devices?
Correct Answer
D. Transformer
Explanation
A transformer operates based on the phenomenon of electromagnetic induction, where an alternating current in one wire (primary coil) induces a current in another nearby wire (secondary coil). This allows for the transfer of electrical energy from one circuit to another at a different voltage level. Transformers are commonly used in power distribution systems to step up or step down voltage levels for efficient transmission and use of electrical energy.
2.
The buoyant force exerted by a fluid on an entirely submerged object is equal to _________________.
Correct Answer
D. The weight of the fluid displaced by the submerged object
Explanation
The buoyant force exerted by a fluid on an entirely submerged object is equal to the weight of the fluid displaced by the submerged object. This is known as Archimedes' principle, which states that the buoyant force is equal to the weight of the fluid that is displaced by the object. The weight of the fluid displaced is directly proportional to the volume of the object submerged and the density of the fluid. Therefore, the correct answer is the weight of the fluid displaced by the submerged object.
3.
What is the kinetic energy of a 12-kg toy car moving at a velocity of 3m/s?
Correct Answer
B. 54J
Explanation
The kinetic energy of an object is given by the equation KE = 1/2 * mass * velocity^2. In this case, the mass of the toy car is 12 kg and the velocity is 3 m/s. Plugging these values into the equation, we get KE = 1/2 * 12 kg * (3 m/s)^2 = 1/2 * 12 kg * 9 m^2/s^2 = 54 J. Therefore, the correct answer is 54J.
4.
Compounds that have the same molecular formula but different chemical structures are called _________________.
Correct Answer
D. Isomers
Explanation
Isomers are compounds that have the same molecular formula but different chemical structures. This means that they have the same number and types of atoms, but the arrangement of these atoms is different. Isomers can have different physical and chemical properties due to their different structures.
5.
___________ states that the volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant.
Correct Answer
A. Boyle's Law
Explanation
Boyle's Law states that the volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant. This means that as the pressure on a gas increases, the volume it occupies decreases, and vice versa. This relationship is described by the equation PV = k, where P is the pressure, V is the volume, and k is a constant. Boyle's Law is named after Robert Boyle, who first stated this principle in the 17th century.
6.
A bond in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other, is called a __________.
Correct Answer
B. Ionic bond
Explanation
An ionic bond is formed when one or more electrons are transferred from one atom to another, creating positive and negative ions. These ions are then attracted to each other due to their opposite charges, resulting in the formation of an ionic bond. This type of bond typically occurs between a metal and a non-metal.
7.
When dissolved in water, bases have all of the following properties except _______________.
Correct Answer
A. Have a sour taste.
Explanation
Bases are substances that release hydroxide ions (OH-) when dissolved in water. They have a bitter taste, change red litmus paper to blue, feel slippery, and conduct electricity. However, they do not have a sour taste. Acids, on the other hand, have a sour taste. Therefore, the correct answer is "have a sour taste."
8.
The reaction of methane with oxygen has the following unbalanced equation: CH₄(g) + O₂(g) CO₂(g) + H₂O(l). The coefficient for oxygen in the balanced equation is ______.
Correct Answer
B. 2
Explanation
In order to balance the equation, the number of oxygen atoms on both sides of the equation should be equal. Since there are 2 oxygen atoms on the right side (CO₂ and H₂O), the coefficient for oxygen in the balanced equation is 2.
9.
What wave propagation principle accounts for the apparent increase in frequency as a train whistle approaches and the apparent decrease in frequency as it moves away?
Correct Answer
D. Doppler effect
Explanation
The Doppler effect is the correct answer because it explains the apparent increase in frequency of a sound wave when the source is moving towards the observer and the apparent decrease in frequency when the source is moving away. This effect occurs due to the compression or stretching of the sound waves as the source moves, causing a change in the perceived frequency. Refraction, reflection, and diffraction do not account for this specific phenomenon.
10.
Melting ice is an example of increasing ___________.
Correct Answer
A. Entropy
Explanation
Melting ice is an example of increasing entropy. Entropy is a measure of the disorder or randomness of a system. When ice melts, the solid molecules become more disordered as they transition into a liquid state. This increase in disorder corresponds to an increase in entropy.