A chemical equation is a representation of a chemical reaction, where reactants under certain chemical conditions react with each other to form products. A chemical equation is written a specific way to show reactants and products, with an arrow separating reactants from products. In reactions with more than one reactant or product, plus signs separate the individual products and reactants from each other. Numbers called coefficients, placed in front of each reactant, specify the ratio required to convert all of the reactants to products. Products also have coefficients that indicate the ratio of each of the products in the reaction. The subscripts after a chemical element tell how many atoms of that element are present in the molecule. For example, the chemical equation for the formation of sugar from water and carbon dioxide is as follows: 6CO2 + 6H2O → C6H12O6 + 6O2 The equation obeys the law of conservation of mass and is called a balanced chemical equation. The law states that the mass of the reactants must equal the mass of the products. This can be determined by counting the number of atoms of each element to verify that there is the same number of atoms in the reactants as in the products.  Ozone (O3) is produced in the upper atmosphere when oxygen gas (O2) absorbs high-energy sunlight. Which equation correctly describes this reaction?

The Japan Trench off the coast of Japan is part of the boundary between an oceanic plate called the Pacific plate and a continental plate called the Eurasian plate. At the trench, the Pacific plate is forced beneath the Eurasian plate, causing earthquakes in Japan. The Japan Trench is an example of which type of crustal feature?

Which of the following is implied by the fact that seafloor spreading at the Mid-Atlantic Ridge is causing the Atlantic Ocean to widen by about 5 centimeters a year?

Consider the following information:

Waves are disturbances that propagate energy through a medium. Propagation of the energy depends on interactions between the particles that make up the medium. Particles move as the waves travel, but there is no net motion of particles. Thus, mechanical waves require matter through which to propagate. These waves are of the following types:

• Longitudinal waves: Movement of the particles is parallel to the direction the wave travels; that is, the direction of displacement is the same as the direction of propagation. Sound waves are longitudinal waves.

• Transverse waves: Movement of the particles is perpendicular to the direction the wave travels; that is, the direction of displacement is perpendicular to the direction of propagation. Movement of a wave through a stretched rope or a trampoline is an example of this type of wave.

Wavelength (λ) is the distance between identical points in the adjacent waves such as from crest to crest or trough to trough. It is measured in meters.

Frequency (f) describes the number of waves that passes a fixed place in a given amount of time. It is measured in hertz or cycles/s.

A period (T) is the time needed for one complete cycle of vibration to pass through a given point. Frequency (f) and period (T) have a reciprocal relationship that can be expressed mathematically as:

T = total time / number of cycles

→ T = 1 / frequency = 1 / f

The wave equation states the mathematical relationship between the speed (v) of a wave and its wavelength (λ) and frequency (f):

Speed = wavelength x frequency

→ v = λ x f

Or:

V = f / T since λ = 1 / f

The amplitude (A) of a wave refers to the maximum amount of displacement of a particle of the medium from its rest position

A transverse wave is transporting energy from east to west. The particles of the medium will move in which direction?

Consider the following information:
Henri stops at a gas station and buys a cup of coffee that he heats in a microwave oven. He then proceeds on his way, enjoying music on the radio in his car. Some miles down the road, he is involved in an accident. Paramedics take him to a nearby hospital for a CT scan.

Of all of the types of radiation mentioned in the passage, which one causes the LEAST amount of damage to living tissue and DNA with
long-term exposure?

Consider the following information:

An important effect of heat is that it can produce a change of state. Matter exists in any of the three states–solid, liquid, or gas. In a gas, the particles can move around freely and independently. In a liquid, particle movement is a bit constrained and limited to sliding and flow movement within its volume. In a solid, particle movement is restricted to only vibrational motion of particles in their fixed positions.

Thus, a change of matter from one physical state to another is called change of state. The state of matter depends on its temperature and the pressure that is exerted on it.

There are six distinct changes of phase that happen to different substances at different temperatures:

• Freezing – A substance changes from a liquid to a solid.

• Melting – A substance changes from a solid to a liquid.

• Condensation – A substance changes from a gas to a liquid.

• Evaporation or vaporization – A substance changes from a liquid to a gas.

• Sublimation – A substance changes directly from a solid to a gas without going through the liquid state.

• Deposition – A substance changes directly from a gas to a solid without going through the liquid state.
In warm, humid weather, people who wear glasses experience a very common effect of phase change while getting off an air-conditioned bus: their glasses suddenly fog up. After a while, the glasses become clear again. Which of the following physical processes are involved in these phenomena?

Consider the following information:

An important effect of heat is that it can produce a change of state. Matter exists in any of the three states–solid, liquid, or gas. In a gas, the particles can move around freely and independently. In a liquid, particle movement is a bit constrained and limited to sliding and flow movement within its volume. In a solid, particle movement is restricted to only vibrational motion of particles in their fixed positions.

Thus, a change of matter from one physical state to another is called change of state. The state of matter depends on its temperature and the pressure that is exerted on it.

There are six distinct changes of phase that happen to different substances at different temperatures:

• Freezing – A substance changes from a liquid to a solid.

• Melting – A substance changes from a solid to a liquid.

• Condensation – A substance changes from a gas to a liquid.

• Evaporation or vaporization – A substance changes from a liquid to a gas.

• Sublimation – A substance changes directly from a solid to a gas without going through the liquid state.

• Deposition – A substance changes directly from a gas to a solid without going through the liquid state.

Which of the following is NOT a property of a gas?

Consider the following information:
Newton’s first law of motion states that an object continues to be in a state of rest or motion unless it is acted on by an external force. The net force acting on the body is the total of all the forces acting on the body. Newton’s first law is sometimes called the law of inertia, which is the tendency of an object to resist changes in velocity. Inertia of an object is directly proportional to its mass.
A book is placed on a dashboard of a car that is stopped at a traffic light. As the car starts to move forward, the book slides off the dashboard. Pick the most correct explanation for the book sliding off the dashboard.

Consider the following information:

Newton’s second law is given by the equation:

a = F/m

Where:

a is the acceleration of an object in m/s²
F is the force applied to the object, and
m is the mass of the object being accelerated in kilograms.

Recall that acceleration is the rate of change of velocity of an object; that is,

a = v/t

A soccer ball weighing 500 g is lying near the center line of the field. A player kicks it with a force of 400 N. What is the velocity of the ball after 5 seconds?

Consider the following information:

Newton’s second law is given by the equation:

a = F/m

Where:

a is the acceleration of an object in m/s²
F is the force applied to the object, and
m is the mass of the object being accelerated in kilograms.

Recall that acceleration is the rate of change of velocity of an object; that is,

a = v/t

A driver accelerates his car first at a rate of 1.8 m/s 2 and then at a rate of 1.2 m/s 2 . What will be the ratio of the two forces exerted by the engine at the two rates?

Consider the following information:

Newton’s second law is given by the equation:

a = F/m

Where:

a is the acceleration of an object in m/s²
F is the force applied to the object, and
m is the mass of the object being accelerated in kilograms.

Recall that acceleration is the rate of change of velocity of an object; that is,

a = v/t

Pick the best option for the blank:
A train with cars of equal masses is moving with constant velocity along a level section of track. The net force on the first car is _________ the net force on the last car.

Consider the following information:
Newton’s third law states that all forces come in pairs. The two forces in the pair are equal in strength and opposite in direction.
The action and reaction forces referred to in Newton’s third law must act on ________ objects.

Consider the following information:

When a force acts on an object to cause a displacement (d) of the object, it is said that work (W) was done on the object.

Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation:

Power (P) = work (W) / time (t)

→ P = [ force (F) x displacement (dx) ] / t

→ P = F x velocity (v)

→ P = Fv

When a force acts on an object to cause a displacement (d) of the object, it is said that work (W) was done on the object.
Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation:
Power (P) = work (W) / time (t)
→ P = [ force (F) x displacement (dx) ] / t
→ P = F x velocity (v)
→ P = Fv
A man does a push-up by applying a force, which results in 0.50 J of work. If it takes 2 seconds to do the push-up, what is his power?

Consider the following information:

When a force acts on an object to cause a displacement (d) of the object, it is said that work (W) was done on the object.

Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation:

Power (P) = work (W) / time (t)

→ P = [ force (F) x displacement (dx) ] / t

→ P = F x velocity (v)

→ P = Fv

When a force acts on an object to cause a displacement (d) of the object, it is said that work (W) was done on the object.
Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation:
Power (P) = work (W) / time (t)
→ P = [ force (F) x displacement (dx) ] / t
→ P = F x velocity (v)
→ P = Fv
Use your understanding of work and power to answer the following question.
Two teammates, Randy and Aaron, are in the weight-lifting room. Randy lifts the 100-pound barbell over his head 10 times in 5 minutes; Aaron lifts the same 100-pound barbell over his head 10 times in 3 minutes. Which teammate delivers the most power?

Consider the following information:

When a force acts on an object to cause a displacement (d) of the object, it is said that work (W) was done on the object.

Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation:

Power (P) = work (W) / time (t)

→ P = [ force (F) x displacement (dx) ] / t

→ P = F x velocity (v)

→ P = Fv

When a force acts on an object to cause a displacement (d) of the object, it is said that work (W) was done on the object.
Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation:
Power (P) = work (W) / time (t)
→ P = [ force (F) x displacement (dx) ] / t
→ P = F x velocity (v)
→ P = Fv
The power of a motor pump is 2 kW. How much water per minute can the pump raise to a height of 10 m? (Under the influence of gravitational force, work = mass (m) × gravitational field strength (g) × height (h), where g = 10 ms^–2 .)

A chemical equation is a representation of a chemical reaction, where reactants under certain chemical conditions react with each other to form products. A chemical equation is written a specific way to show reactants and products, with an arrow separating reactants from products. In reactions with more than one reactant or product, plus signs separate the individual products and reactants from each other. Numbers called coefficients, placed in front of each reactant, specify the ratio required to convert all of the reactants to products. Products also have coefficients that indicate the ratio of each of the products in the reaction.

The subscripts after a chemical element tell how many atoms of that element are present in the molecule. For example, the chemical equation for the formation of sugar from water and carbon dioxide is as follows:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

The equation obeys the law of conservation of mass and is called a balanced chemical equation. The law states that the mass of the reactants must equal the mass of the products. This can be determined by counting the number of atoms of each element to verify that there is the same number of atoms in the reactants as in the products.

Iron (Fe) can combine with oxygen (O) to produce any one of the three different iron oxides: FeO, Fe₂O₃, and Fe₃O₄. Of the three oxides, FeO is the most unstable. If FeO is exposed to air, it forms Fe₂O₃. Which equation correctly describes this reaction?

When an allele is represented by a capital letter, it is said to be dominant, and will always be expressed when coupled with another dominant allele. Recessive genes, which are represented by a lowercase letter, are expressed only when an individual is pure and has two copies of the allele.
In kittens, the gene for pointy ears is dominant and the gene for floppy ears is recessive. Kittens will express the pointy ear trait if the kitten is pure for dominant gene or has a hybrid of alleles. In order for floppy ears to be expressed on a kitten, the kitten must be pure for the recessive gene.
Punnett Squares are charts used to predict the odds of specific gene combinations in offspring. Below is a Punnett Square of a cross between two heterozygous parents.
According to the information presented, what genotype should replace the “?” in the Punnett Square?

When an allele is represented by a capital letter, it is said to be dominant, and will always be expressed when coupled with another dominant allele. Recessive genes, which are represented by a lowercase letter, are expressed only when an individual is pure and has two copies of the allele.
In kittens, the gene for pointy ears is dominant and the gene for floppy ears is recessive. Kittens will express the pointy ear trait if the kitten is pure for dominant gene or has a hybrid of alleles. In order for floppy ears to be expressed on a kitten, the kitten must be pure for the recessive gene.
Punnett Squares are charts used to predict the odds of specific gene combinations in offspring. Below is a Punnett Square of a cross between two heterozygous parents.
The genotypic ratio of this Punnett Square is best expressed as

Nearly 75% of plant and animal species on Earth, including all non-bird dinosaurs, went extinct during the Cretaceous-Paleogene (or Cretaceous-Tertiary) extinction event. Scientists have spent years speculating about what precipitated this extinction. Various hypotheses have been presented to account for the disappearance of these huge creatures. The prevailing theory is that a large asteroid collided with Earth and its impact raised a cloud of dust that prevented sunlight from reaching the planet's surface for many years. Temperatures fell rapidly, and without sunlight, much of the plant life on the planet's surface disappeared. Without warmth or food, the dinosaurs, as well as many other species, became extinct.
In support of this theory, scientists have found a thin layer of sediment in marine and terrestrial rocks that contains metals that are rare on Earth but abundant in asteroids. Additionally, a large crater was found in the Gulf of Mexico that must have been formed when an asteroid hit Earth at roughly the same time as the extinctions took place.
Amid the destruction was opportunity for evolution. There were countless vacated ecological niches and the surviving organisms rapidly adapted and developed in order to occupy these niches. It is believed that several of the mammals, including primates, that are alive today developed during this time.
If the preceding information is true, which of the following is the most likely explanation for the fact there is still life on Earth today?

Nearly 75% of plant and animal species on Earth, including all non-bird dinosaurs, went extinct during the Cretaceous-Paleogene (or Cretaceous-Tertiary) extinction event. Scientists have spent years speculating about what precipitated this extinction. Various hypotheses have been presented to account for the disappearance of these huge creatures. The prevailing theory is that a large asteroid collided with Earth and its impact raised a cloud of dust that prevented sunlight from reaching the planet's surface for many years. Temperatures fell rapidly, and without sunlight, much of the plant life on the planet's surface disappeared. Without warmth or food, the dinosaurs, as well as many other species, became extinct.
In support of this theory, scientists have found a thin layer of sediment in marine and terrestrial rocks that contains metals that are rare on Earth but abundant in asteroids. Additionally, a large crater was found in the Gulf of Mexico that must have been formed when an asteroid hit Earth at roughly the same time as the extinctions took place.
Amid the destruction was opportunity for evolution. There were countless vacated ecological niches and the surviving organisms rapidly adapted and developed in order to occupy these niches. It is believed that several of the mammals, including primates, that are alive today developed during this time.
If Charles Darwin read this passage, would he agree with the statements made in the last paragraph?

If you cut a horizontal cross section through the trunk of a tree, you can see the tree's growth rings (also known as tree rings). Each ring inside the trunk of a tree represents the annual growth of the tree. There are two parts of a growth ring. The inner part is formed during the early growth season (spring and early summer in North America) and is relatively less dense. The outer part of each ring is denser and is formed during the late summer and autumn.
The growing conditions of a particular year will affect the size of a ring. In ideal growing conditions (such as adequate moisture and a relatively long growing season), a ring may be larger because the tree was able to grow more during that time. However, a cold summer or a drought can cause the ring size to be smaller than normal.
Researchers can use tree rings to learn about the growing conditions that were present during a particular time period. The tree depicted below was cut down at the end of the growing year in 2000.
Based on the figure, which of the following years was the best growing season?

If you cut a horizontal cross section through the trunk of a tree, you can see the tree's growth rings (also known as tree rings). Each ring inside the trunk of a tree represents the annual growth of the tree. There are two parts of a growth ring. The inner part is formed during the early growth season (spring and early summer in North America) and is relatively less dense. The outer part of each ring is denser and is formed during the late summer and autumn.
The growing conditions of a particular year will affect the size of a ring. In ideal growing conditions (such as adequate moisture and a relatively long growing season), a ring may be larger because the tree was able to grow more during that time. However, a cold summer or a drought can cause the ring size to be smaller than normal.
How old is the tree represented in the figure?

Which of the following organisms in the food web above are eaten by both land and sea creatures?

The absence of _______ on the food web above would most devastate the rest of the web.

The kidneys of the urinary system remove cellular wastes and excess water from the blood. This material, called urine, is stored in the bladder until it is excreted from the body.
A urologist is a doctor who specializes in disorders of the urinary system. Which of the following patients is most likely to be treated by a urologist?