Science 8: Benchmark III-part 1 (50)

A push or pull refers to a force. Force is a physical quantity that can cause an object to accelerate, change its shape, or change its state of motion. It can be exerted by objects or living beings, and it can be measured in units such as Newtons. Therefore, force is the correct answer in this case as it accurately describes the concept of a push or pull.

Ice melting is an example of a physical change because it involves a change in the state of matter from solid to liquid, without any alteration in the chemical composition of the substance. The molecules in the ice rearrange themselves and gain enough energy to break the intermolecular forces holding them together, resulting in the formation of liquid water. This change is reversible, as the liquid water can be frozen back into ice by removing heat.

The Law of Conservation of Matter states that matter cannot be created nor destroyed in a chemical reaction. This means that the total mass of the reactants must be equal to the total mass of the products. While matter can undergo physical and chemical changes, the total amount of matter in a closed system remains constant. This law is a fundamental principle in chemistry and is supported by numerous experimental observations.

Freezing is the process in which a liquid changes to a solid state. During freezing, the molecules of the liquid slow down and come closer together, forming a solid structure. This process typically occurs when the temperature of the liquid is lowered below its freezing point.

A reference point is a place or object that is used as a comparison to determine if something is in motion. It serves as a fixed point of comparison, allowing us to observe the movement of other objects or places in relation to it. By comparing the position of the object or place of interest to the reference point, we can determine if it is moving or not.

Mass is the amount of matter in an object. It is a fundamental property of an object and is measured in kilograms. Mass determines the object's inertia and is a measure of the object's resistance to changes in its motion. Therefore, mass is the correct answer to the question as it directly relates to the amount of matter present in an object.

When an acid and base combine in a neutralization process, they react to form salt and water. This reaction occurs when the hydrogen ions from the acid combine with the hydroxide ions from the base to form water, while the remaining ions from the acid and base combine to form a salt. This process is called neutralization because it results in the formation of a neutral substance, which is neither acidic nor basic.

A crystal is an orderly arrangement of molecules found in solids such as diamonds or ice. In a crystal, the molecules are arranged in a repeating pattern, forming a three-dimensional lattice structure. This arrangement gives crystals their characteristic shape and properties.

The best unit of measurement to use when measuring a pencil in science would be centimeters. Centimeters are a more appropriate unit for measuring small objects like pencils because they provide a more precise measurement compared to inches. Additionally, centimeters are commonly used in scientific measurements and are part of the metric system, which is the standard system of measurement in science.

H2O is a compound because it consists of two different elements, hydrogen (H) and oxygen (O), combined together in a fixed ratio. Compounds are formed when elements chemically react and bond with each other to form a new substance with different properties. In the case of H2O, the hydrogen and oxygen atoms combine through covalent bonding to create water, which is a compound with distinct physical and chemical properties. N2, Cl2, and He are not compounds as they consist of only one type of element and do not undergo any chemical bonding.

A spring scale measures force. Force is a physical quantity that can cause an object to accelerate or deform. A spring scale works by using Hooke's law, which states that the force exerted by a spring is directly proportional to the amount the spring is stretched or compressed. By measuring the displacement of the spring, the scale can determine the force applied to it. Therefore, a spring scale is specifically designed to measure force and is commonly used to measure the weight of objects.

Absolute zero is the temperature at which molecular motion ceases completely. It is the lowest possible temperature that can be reached, where all particles have minimal energy and motion. At this temperature, molecules stop vibrating and moving, resulting in a complete absence of molecular motion. Therefore, absolute zero is the temperature when there is no molecular motion.

An object's speed does not change when it is moving at a constant speed. This means that the object is moving at the same rate, without any increase or decrease in its velocity. In other words, the object covers equal distances in equal intervals of time. When an object has constant speed, there is no acceleration, which is the rate of change of velocity. Therefore, constant speed is the correct answer as it indicates that the object's speed remains the same over time.

Work is a measure of the energy transferred to or from an object by the application of force along a displacement. The unit of measurement for work is the joule, which is defined as the amount of work done when a force of one newton is applied over a distance of one meter in the direction of the force. Therefore, the correct answer is joule.

A compound is a "pure" substance that is made of "more than one" element. It is formed when different elements chemically combine in fixed proportions. Compounds have a specific chemical formula and their properties are different from the elements they are made of. Therefore, a compound is the correct answer to the question.

The biggest problem and negative effect of nuclear energy is the storage and disposal of waste products. Nuclear power plants generate radioactive waste that remains hazardous for thousands of years. Finding safe and secure methods to store and dispose of this waste is a significant challenge. If not properly managed, it can pose serious health and environmental risks. The long-term storage and disposal of nuclear waste require careful planning and implementation to ensure the safety of future generations.

Tearing paper is an example of a physical change because it does not change the chemical composition of the paper. The paper remains paper even after it is torn into smaller pieces. Physical changes only affect the physical properties of a substance, such as shape, size, or state of matter, without altering its chemical makeup. In this case, tearing the paper only alters its appearance and does not create any new substances.

Newton's Third Law of Motion states that every action has an equal and opposite reaction force. This means that for every force exerted on an object, there is an equal force exerted in the opposite direction. For example, if you push a wall, the wall pushes back with the same amount of force. This law explains the concept of action and reaction forces and is applicable to various scenarios, such as the propulsion of a rocket or the movement of a person walking.

Inertia is the tendency of an object to resist any changes in its motion. It is a property of matter that causes objects to stay at rest or in motion unless acted upon by an external force. This means that an object will continue moving at a constant speed in a straight line or remain at rest unless a force is applied to change its state of motion. Inertia is directly related to an object's mass, with larger objects having more inertia and being harder to move or stop.

The right side of a chemical equation is called the product. In a chemical reaction, reactants are the substances that undergo a chemical change, while products are the new substances that are formed as a result of the reaction. The product side of the equation represents the substances that are produced after the reaction has occurred.

Weight is the correct answer because weight is the measure of the force of gravity acting on an object, while mass is the measure of the amount of matter in an object. Since the moon has less gravity than Earth, an object's weight would be less on the moon compared to Earth, but its mass would remain the same. Therefore, the change would be in weight, not mass.

Ionic and covalent are two types of chemical bonding. Ionic bonding occurs when there is a transfer of electrons between atoms, resulting in the formation of ions with opposite charges that attract each other. Covalent bonding, on the other hand, occurs when atoms share electrons to achieve a full outer shell. In this type of bonding, atoms are held together by the shared electrons. Therefore, ionic and covalent are the correct answers as they represent the two main types of chemical bonding.

The amount of work done in a period of time is determined by power. Power is the rate at which work is done or the amount of work done per unit of time. It is calculated by dividing the work done by the time taken. Therefore, power is the correct answer as it directly relates to the amount of work done in a given time period.

When a neutral atom loses or gains an electron, it becomes an ion. Ions are formed when atoms either gain or lose electrons, resulting in a positive or negative charge. This process is known as ionization. Isotopes, on the other hand, refer to atoms of the same element that have different numbers of neutrons. Compounds are substances formed by the chemical combination of two or more elements. Therefore, the correct answer is ion.

Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This law is represented by the equation F=ma, where F is the net force applied to the object, m is its mass, and a is the resulting acceleration. Therefore, the correct answer is Newton's Second Law of Motion.

In a chemical equation, the substance to the left of the arrow is called a reactant. Reactants are the starting materials that undergo a chemical reaction to form the products. They are typically written on the left side of the equation and are consumed during the reaction. The reactants are the substances that are present before the reaction occurs and are necessary for the reaction to take place.

An object's motion depends on both its mass and velocity. Mass refers to the amount of matter an object has, while velocity refers to the speed and direction of its motion. The greater the mass of an object, the more force is needed to move it. Similarly, the greater the velocity of an object, the faster it moves and the more force it possesses. Therefore, both mass and velocity play a crucial role in determining the motion of an object.

Heat always moves from higher temperature to lower temperature. This is because heat is a form of energy that naturally flows from areas of high temperature to areas of low temperature. This process is known as heat transfer and it occurs until equilibrium is reached, meaning that the temperatures of the objects or substances involved become equal.

Power is the rate at which work is done or energy is transferred. It is calculated by dividing the amount of work done by the time taken to do it. Therefore, power represents the amount of work done in a period of time. It is a measure of how quickly or efficiently work is being done.

Acceleration is the rate of change of velocity. It measures how quickly an object's velocity is changing over time. When an object's velocity increases or decreases, it is experiencing acceleration. Therefore, acceleration is the correct answer to the question as it represents the rate of change of velocity.

Terminal velocity is the term used to describe the maximum velocity reached by an object falling through a fluid, such as air or water, when the force of gravity pulling the object downward is balanced by the drag force exerted by the fluid. At terminal velocity, the object stops accelerating and continues to fall at a constant speed. Therefore, terminal velocity is the correct answer as it refers to the point at which an object reaches its greatest velocity during free fall.

The force of gravity on a person or object at the surface of a planet is referred to as weight. Weight is the measure of the gravitational force acting on an object due to its mass. It is the force that pulls objects towards the center of the planet. The weight of an object can vary depending on the mass of the object and the strength of the gravitational field on the planet's surface.

Pure water has a pH of 7, which is considered neutral. This means that the concentration of hydrogen ions (H+) and hydroxide ions (OH-) in water is equal, resulting in a balanced pH level. A pH of 7 indicates that the water is neither acidic nor alkaline, making it neutral.

Speed is the correct answer because it refers to the distance an object travels in a certain amount of time. It is a scalar quantity that measures how fast an object is moving without considering its direction. Acceleration refers to the rate of change of velocity, velocity refers to the rate of change of displacement, and inertia refers to an object's resistance to changes in its motion.

The distance an object travels in a certain amount of time is determined by its speed. Speed is a scalar quantity that represents how fast an object is moving, regardless of its direction. It is calculated by dividing the distance traveled by the time taken. Therefore, speed is the correct answer to the question.

Fission is the correct answer because it refers to the type of nuclear reaction that releases energy or splits the nucleus. In a fission reaction, the nucleus of an atom is divided into two smaller nuclei, accompanied by the release of a large amount of energy. This process is commonly used in nuclear power plants and atomic bombs. Fusion, on the other hand, is the process of combining two smaller nuclei to form a larger nucleus, which also releases energy, but it is not the type of reaction described in the question.

Rubbing alcohol, C3H7OH, contains 3 carbon atoms, 8 hydrogen atoms, and 1 oxygen atom. This is because the chemical formula of rubbing alcohol represents the number and type of atoms present in the molecule. The subscript numbers indicate the number of atoms of each element. Therefore, the correct answer is C=3 H=8 O=1.

Gravity is the force that keeps a satellite in orbit. Gravity is the attractive force between two objects with mass, and it pulls the satellite towards the center of the Earth. This force acts as a centripetal force, constantly changing the direction of the satellite's motion and preventing it from flying off into space. Without gravity, the satellite would continue moving in a straight line and eventually leave its orbit.

The given formula, Cl2 + 2Na -> 2NaCl, is a balanced formula. This is because the number of atoms on both sides of the equation is equal, indicating that the law of conservation of mass is satisfied. The coefficient "2" in front of NaCl ensures that there are two sodium atoms and two chlorine atoms on both sides. Therefore, the formula is balanced.

Newton's First Law of Inertia states that an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity, unless acted upon by an unbalanced force. This law is also known as the law of inertia, which describes the tendency of objects to resist changes in their motion. It explains why objects tend to maintain their state of motion unless an external force is applied to them.

Group 1 on the periodic table is the most reactive because elements in this group, also known as the alkali metals, have only one valence electron. This makes them highly likely to lose that electron and form positive ions, resulting in strong reactivity. Additionally, alkali metals have low ionization energies and electronegativities, further contributing to their reactivity.

Inertia is the tendency of an object to stay in motion or remain at rest unless acted upon by an outside force. This means that an object will continue moving in a straight line with constant velocity or stay still unless a force is applied to change its state of motion. Inertia is a fundamental property of matter and is related to the mass of an object. The greater the mass, the greater the inertia, and the harder it is to change the object's motion.

The product of an object's mass and its velocity is known as momentum. Momentum is a vector quantity that describes the motion of an object and is calculated by multiplying the mass of the object by its velocity. It is a measure of how difficult it is to stop or change the direction of an object's motion. Higher mass or higher velocity will result in a higher momentum. Therefore, momentum is the correct answer for this question.

Velocity is the correct answer because it is defined as the speed of an object in a specific direction. It takes into account both the magnitude of the speed and the direction in which the object is moving. Therefore, velocity is the term used to describe speed in a certain direction.

Ions, which are atoms or groups of atoms with positive or negative charges, help make up salts. Salts are compounds formed when an acid reacts with a base, resulting in the formation of positive and negative ions. The positive ion comes from the base, while the negative ion comes from the acid. Therefore, salts are made up of ions and are formed through the combination of acids and bases.

Newton's 3rd Law of Motion states that for every action, there is an equal and opposite reaction. In the case of a rocket taking off into space, the action is the expulsion of gases from the rocket's engines, and the reaction is the force that propels the rocket forward. This law explains how the rocket is able to overcome the force of gravity and move upward into space.

Newton's 1st law of motion, also known as the law of inertia, states that an object at rest will stay at rest, and an object in motion will continue moving with a constant velocity, unless acted upon by an external force. This law describes the tendency of objects to resist changes in their state of motion and is the foundation for understanding the behavior of objects in the absence of external forces.

The acceleration of a moving object depends on the force applied to it and its mass. Force is the cause of acceleration, and the greater the force applied to an object, the greater its acceleration will be. Additionally, the mass of the object also plays a role, as objects with larger mass require more force to accelerate compared to objects with smaller mass. Therefore, the correct answer is force and mass of the object.

Salt lowers the freezing point of water below 0 degrees Celsius. When salt is added to ice on a sidewalk, it dissolves in the water molecules present in the ice. This dissolution disrupts the formation of ice crystals, causing the freezing point of the water to decrease. As a result, the ice begins to melt at a temperature below 0 degrees Celsius. This is why salt is commonly used to melt ice and prevent the formation of ice on sidewalks.

N2 is a covalent bond because it consists of two nitrogen atoms, which are both nonmetals. In a covalent bond, the atoms share electrons to achieve a stable electron configuration.