1. What is the pH level of pure water at 25°C (77°F)?
b) Pure water has a neutral pH of 7 at 25°C (77°F). The pH scale ranges from 0 to 14, with 7 being neutral, below 7 being acidic, and above 7 being basic (alkaline).
2. What type of bond is formed when two atoms share electrons?
b) A covalent bond is formed when two atoms share pairs of electrons to achieve a full outer shell and become more stable. This type of bond commonly occurs between nonmetal atoms.
3. What is the primary function of ribosomes in a cell?
b) Ribosomes are the cellular structures responsible for protein synthesis. They read the messenger RNA (mRNA) sequence and translate it into a polypeptide chain (protein).
4. Which part of the brain is primarily responsible for regulating balance and coordination?
b) The cerebellum is the part of the brain that plays an essential role in motor control, coordination, precision, and timing of movements. It helps maintain balance and posture.
5. What is the speed of light in a vacuum?
a) The speed of light in a vacuum is approximately 300,000 kilometers per second (km/s) or about 186,282 miles per second. This speed is a fundamental constant in physics.
6. What is the most abundant gas in the Earth’s crust?
b) Oxygen
Explanation: Oxygen is the most abundant element in the Earth’s crust, primarily found in the form of oxides and silicates. It makes up about 46% of the Earth's crust by weight.
7. Which law explains the relationship between the pressure and volume of a gas at constant temperature?
b) Boyle's Law states that the pressure of a given amount of gas is inversely proportional to its volume at a constant temperature. This means that as the volume of a gas decreases, its pressure increases, and vice versa.
8. Which element is the primary component of organic molecules?
d) Carbon is the backbone of all organic molecules. It forms the basis of life on Earth due to its ability to form stable bonds with many elements, including itself, which allows for the complexity of organic chemistry.
9. Which of the following is a macronutrient required by plants?
C) Magnesium is a macronutrient required by plants as it is a central component of the chlorophyll molecule, which is necessary for photosynthesis. While zinc, iron, and manganese are also essential, they are considered micronutrients.
10. What is the primary difference between AC (Alternating Current) and DC (Direct Current)?
c) AC (Alternating Current) is an electric current that periodically reverses direction, while DC (Direct Current) flows in one constant direction. AC is commonly used for power transmission because it can be easily transformed to different voltages, while DC is used in batteries and electronic devices.
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