SECTION A
Janice is learning about compounds. Which of the following best describes a compound?
A) A substance made up purely of one element
B) A group of substances that are either acids or bases
C) a group of substances that can be separated by a physical change
D) a substance made up of two or more elements that are chemically combined
D) a substance made up of two or more elements that are chemically combined
What type of mixture is shown in a diagram shows evenly spread identical particles dissolved in water?
A. Heterogeneous
B. Solution
C. Mechanical mixture
D. Colloidal solid
B. Solution
Lemon juice has a pH of 2. Using the pH scale, describe whether this substance is acidic, neutral, or basic and explain your reasoning.
It is acidic because 2 lies in the region of strong acids, which are from 0-3pH
Element
A pure substance containing only one type of atom
A scientist is studying why a particular species of plant grows significantly taller in one valley compared to a nearby valley with the same soil type. The scientist gathers temperature data, rainfall patterns, hours of sunlight, and nutrient levels from both locations. Before designing the experiment, the scientist develops the following statement:
“If plants from both valleys are grown under identical controlled conditions indoors, then any difference in height will still appear.”
Which statement best evaluates whether this is a strong scientific hypothesis?
A. It is not a strong hypothesis because it includes too many variables for the scientist to measure accurately.
B. It is a strong hypothesis because it is a testable prediction based on prior observations and research, rather than a guess.
C. It is not a strong hypothesis because hypotheses must always include mathematical relationships.
D. It is a strong hypothesis because any statement beginning with “if” and “then” is automatically scientific.
B. It is a strong hypothesis because it is a testable prediction based on prior observations and research, rather than a guess.
Sand and water form what type of mixture?
A. Compound
B. Homogeneous
C. Heterogeneous
D. Solution
C. Heterogeneous
Which method would best separating a solution?
A. Filtration
B. Sorting
C. Distillation
D. Sieving
C. Distillation
A student heats a beaker of water and observes that sugar dissolves faster at 70°C than at 20°C. Using particle motion, explain why temperature affects dissolution rate.
Soluble objects dissolve more quickly when the temperature increases.
Base - What charge particles do they produce and where are they on the pH scale?
-/negative charges
they are from 8-14 on the pH scale
Astronomers discover a new object orbiting a distant star. Initial measurements show the object has no solid surface, a very low average density, and an atmosphere composed almost entirely of hydrogen and helium. However, it is only about twice the diameter of Earth and does not display the extreme gravitational pull typical of large planets.
Based on the characteristics of known planets in our solar system, which evaluation is most scientifically accurate?
A. It must be classified as a gas giant because its atmosphere matches hydrogen–helium composition, regardless of size.
B. It cannot be a planet because any object without a rocky surface must be classified as a star or brown dwarf.
C. It is unlikely to be classified as a gas giant because gas giants in our solar system possess both hydrogen–helium atmospheres and extremely large size and mass.
D. It should be classified as a terrestrial planet because its radius is close to Earth’s radius, even if it lacks a rocky surface.
C. It is unlikely to be classified as a gas giant because gas giants in our solar system possess both hydrogen–helium atmospheres and extremely large size and mass.
In saltwater, salt is the—
A. Solvent
B. Solute
C. Saturation point
D. Precipitate
B. Solute
A student is dissolving sugar in room‑temperature water. After stirring in multiple spoonfuls, the sugar suddenly stops dissolving and begins collecting at the bottom even when stirred vigorously.
Which conclusion best explains the situation?
A. The sugar has become insoluble due to stirring too quickly.
B. The solution has reached its solubility limit at that temperature.
C. The water has chemically changed and can no longer act as a solvent.
D. The undissolved sugar indicates the student added a contaminant to the water.
B. The solution has reached its solubility limit at that temperature.
Explain why a mixture like salad is considered heterogeneous. Include at least two characteristics.
Heterogenous mixtures are very clearly separated substances. The mixture lacks uniformity and can be separated through sorting, which can only be done with heterogenous mixtures.
What is the name of a homogenous mixture that is produced when a solid like salt dissolves and uniformly mixes in water?
Solution
A species of coastal bird has historically fed on small, soft‑shelled crabs. Over several centuries, rising ocean temperatures have caused the soft‑shelled crab population to collapse, while a new population of larger, hard‑shelled crabs has become more common. Only a small number of birds in the original population possess significantly stronger, thicker beaks capable of cracking these new crabs.
Based on the scientific concept of adaptation, which conclusion is most accurate?
A. The entire bird species will quickly evolve thicker beaks within one lifetime as they learn to eat the new crab species.
B. The species is unlikely to survive because adaptation requires all individuals to have the same traits at the same time.
C. Birds with thicker beaks are more likely to survive and reproduce, gradually causing the species to shift toward thicker beaks over many generations.
D. All birds will eventually develop thicker beaks if they continue attempting to crack the hard‑shelled crabs every day.
C. Birds with thicker beaks are more likely to survive and reproduce, gradually causing the species to shift toward thicker beaks over many generations.
A chemist observes a reaction between two substances in a closed container. Which of the following would most likely happen if the temperature is increased inside the container?
A The rate of the reaction would increase.
B The mass of each of the atoms would increase.
C The two substances would release nuclear energy.
D The two substances would not change into different compounds.
A The rate of the reaction would increase.
A scientist receives a liquid sample that looks completely uniform. However, when examined under a microscope, tiny solid particles are visible, unevenly distributed throughout the liquid.
What is the most accurate classification?
A. A homogeneous mixture because it appears uniform to the naked eye.
B. A heterogeneous mixture because the parts are not evenly distributed at the particle level.
C. A compound because solids and liquids are chemically bonded.
D. A solution because all mixtures containing solids are solutions.
B. A heterogeneous mixture because the parts are not evenly distributed at the particle level.
A student mixes salt into water to create a sports drink. After shaking, the salt disappears, and the drink tastes evenly salty.
Which statement correctly applies the relationship between solute and solvent?
A. Water is the solute because it dissolves into the salt.
B. Salt is the solvent because it changes the taste of the drink.
C. Salt is the solute because it dissolves; water is the solvent because it performs the dissolving.
D. Both water and salt are solvents because they mix evenly.
C. Salt is the solute because it dissolves; water is the solvent because it performs the dissolving.
_______________ mixtures have no uniformity
_______________ mixtures have uniformity
Heterogenous/Homogenous
A scientist compares two different solids: Substance A and Substance B.
Both are heated at the same rate using identical equipment. During heating, the scientist observes:
Based on your understanding of energy and matter, which conclusion is most accurate?
A. Substance A must have a higher density because it melts sooner, requiring less energy.
B. Substance B has higher melting and boiling points, meaning it requires more thermal energy input to change state.
C. Substance A and B have identical physical properties because both eventually melted and boiled.
D. Substance A contains more thermal energy naturally, so it melts more easily regardless of temperature.
B. Substance B has higher melting and boiling points, meaning it requires more thermal energy input to change state.
A student adds salt to warm water and observes it dissolves quickly. Why?
A. Pressure is higher
B. Temperature increases dissolution rate
C. Solubility decreases with heat
D. Salt becomes nonpolar
B. Temperature increases dissolution rate
A student places a glow stick in warm water and another glow stick in cold water. She notices the glow stick in warm water becomes brighter quickly.
Which explanation best applies this concept to solutions?
A. Warm water has fewer particles, so dissolved substances become unstable.
B. Temperature increases molecular motion, which increases dissolution rate in solutions.
C. Cold water strengthens chemical bonds, preventing solutes from dissolving.
D. Light energy dissolves into warm water, increasing brightness.
B. Temperature increases molecular motion, which increases dissolution rate in solutions.
A company produces canned carbonated drinks. They increase the pressure inside the cans during production. As a result, more carbon dioxide gas dissolves into the liquid than at normal pressure.
Based on the slideshow’s explanation of dissolution rate, which reasoning best explains why?
A. Higher pressure increases the dissolution of gases into liquids.
B. Pressure has no influence on gas solubility in liquids.
C. Pressure removes thermal energy from the drink, forcing gas to dissolve.
D. Low pressure creates more solvent space for gas molecules to dissolve.
A. Higher pressure increases the dissolution of gases into liquids.
A chemist analyzes an unknown sample that appears uniform when examined with the naked eye. However, under a high‑powered microscope, the chemist observes small, unevenly distributed solid particles suspended throughout the liquid. The chemist must classify the substance.
Which conclusion is most accurate, based on the evidence?
A. The sample is a homogeneous mixture because it looks uniform without magnification.
B. The sample is a heterogeneous mixture because the components are not uniformly distributed at the particle level.
C. The sample is a solution because all mixtures that look uniform must be solutions.
D. The sample is a compound because the substances appear blended together.
B. The sample is a heterogeneous mixture because the components are not uniformly distributed at the particle level.
A geologist studies a mountain range that formed millions of years ago from two continental plates colliding. Over time, the mountains have been heavily weathered. Sediments from the mountains have collected in a nearby basin, where they formed thick layers of sedimentary rock. Recently, tectonic activity has begun to slowly uplift the basin.
Based on your understanding of the rock cycle, what sequence of geological processes is most likely to occur next?
A. The uplifted sedimentary layers will immediately melt into magma, forming intrusive igneous rock at the surface.
B. The uplifted sedimentary layers will experience increased pressure and heat underground, eventually transforming into metamorphic rock before possibly melting.
C. The uplifted sedimentary layers will bypass metamorphism and directly become igneous rock through compaction and cementation.
D. The uplifted sedimentary layers will remain unchanged because once sedimentary rock forms, it cannot transition into other rock types.
B. The uplifted sedimentary layers will experience increased pressure and heat underground, eventually transforming into metamorphic rock before possibly melting.