1.
Which of the following statements is NOT true regarding the relationship between temperature and the solubility of solids in liquids?
Correct Answer
C. The solubility of all solids is affected by changes in temperature.
Explanation
While the solubility of many solids is influenced by temperature changes, there are some solids whose solubility is relatively unaffected by temperature variations. The other options accurately reflect the relationship between temperature and solubility, including the use of temperature changes in recrystallization, a common purification technique for solids.
2.
What is the main source of energy in our solar system?
Correct Answer
D. The Sun
Explanation
The Sun is the main source of energy in our solar system. It emits vast amounts of light and heat through nuclear fusion, which powers all life on Earth. The Sun's energy is essential for photosynthesis, the process by which plants convert sunlight into chemical energy. It also drives weather patterns, ocean currents, and the water cycle. Additionally, solar energy is harnessed through solar panels to generate electricity for human use. Overall, the Sun plays a crucial role in sustaining life and powering various natural processes in our universe.
3.
All matter has mass and takes up
Correct Answer
B. Space
Explanation
The statement "All matter has mass and takes up space" is a fundamental concept in physics. Matter is made up of particles that have mass and occupy physical space. This means that matter cannot exist without occupying a certain amount of space. Therefore, the correct answer is space.
4.
A word that means the same as transformation is
Correct Answer
D. Change
Explanation
The word "change" is the best synonym for "transformation" as it refers to the process of becoming different or altering in some way. It encompasses a broad range of meanings and can be used to describe various types of transformations, such as physical, chemical, or even emotional changes. Therefore, "change" is the most appropriate word that carries a similar meaning to "transformation".
5.
Which of these is an example of a physical change?
Correct Answer
A. Melting ice
Explanation
Melting ice is an example of a physical change because it involves a change in the state of matter from solid to liquid, without altering the chemical composition of the substance. The molecules in ice rearrange themselves when heated, causing the solid ice to transform into liquid water. This change is reversible, as the liquid water can freeze again to form solid ice.
6.
How long does it take for fossil fuels to form?
Correct Answer
C. Millions of years
Explanation
Fossil fuels are formed from the remains of plants and animals that lived millions of years ago. Over time, these remains were subjected to heat and pressure, causing them to undergo chemical changes and transform into the fossil fuels we use today, such as coal, oil, and natural gas. This process takes an extensive amount of time, spanning millions of years, which explains why fossil fuels are considered non-renewable resources.
7.
Which would be an example of a mechanical to thermal energy transformation?
Correct Answer
B. Rubbing your hands together
Explanation
Rubbing your hands together is an example of a mechanical to thermal energy transformation. When you rub your hands together, the friction between them generates heat energy, converting the mechanical energy of the hand movement into thermal energy. This process is known as mechanical friction, where the mechanical energy is transformed into thermal energy due to the resistance between the surfaces in contact.