GED Practice

GED Science Review: Temperature and Heat

Questions:

Directions: Choose the answer to each question.


Questions 1 refer to the following passage and diagram.

          The transfer of heat from one object to another can be explained in terms of moving molecules. The molecules in hot objects have more kinetic energy and move faster than the molecules in cold objects. This molecular motion is measured as temperature. When two objects come in contact with each other, the higher-energy molecules in the warmer object begin to collide with the molecules in the cooler object. Energy is transferred in the process. This model shows that coldness is actually the absence of heat. As heat energy leaves an object, the object becomes less warm, or colder.



  1. As an ice cube in your hand melts, your hand begins to feel cold, Which of the following conclusions about heat transfer is supported by the information in the passage and the diagram?
    • The temperature of the ice decreases.
    • Cold from the ice flows into your hand.
    • The molecules in your hand gain energy.
    • Heat from your hand is absorbed by the ice.
  2. Which statement best predicts what will happen after the objects in contact reach the same temperature?
    • Heat will no longer be transferred from one object to the other.
    • Temperature will no longer depend on the motion of molecules.
    • The object on the right will continue to gain heat and become warmer.
    • The temperature of both objects will increase as heat is transferred from the air.
  3. Heat energy can be transferred in three ways. In convection, heat is transferred by the flow of currents through gases and liquids. In conduction, heat is transferred from molecule to molecule. In radiation, heat is transferred by electromagnetic waves, which can travel through space.



    Questions 4 and 5 refer to the following passage and graphs.

    All substances have a form of stored energy called chemical potential energy. In a chemical reaction, substances called reactants change to produce different substances, products. Energy changes involve breaking and re-forming the bonds that make up these substances. Therefore, the amount of chemical potential energy in the products differs from that in the reactants.
    In an endothermic chemical reaction, more energy is needed to break the bonds in the reactants than is released by forming bonds in the products. This energy may come from the surroundings. In an exothermic reaction, the energy released as the products form is greater than the energy absorbed to break the bonds in the reactants. The graphs show how chemical potential energy changes as these reactions proceed.


     
  4. Which change occurs during an endothermic chemical reaction?
    • Energy is created.
    • Energy is released.
    • Energy is absorbed.
    • Energy is destroyed.
  5. A scientist carries out a reaction in a test tube. After the reaction stops, she notices that the test tube is very warm. What can be concluded about this reaction?
    • The reactants absorb heat energy from their surroundings.
    • The energy of the products is equal to the energy of the surroundings.
    • The produces require more energy to form than is released by the reactants.
    • The chemical potential energy of the reactants is more than that of the products.


  6. Temperatures can be measured on different scales. The table shows the same temperatures on the Fahrenheit scale, the Celsius scale, and the Kelvin scale.

    Coffee is often brewed at 170˚F. How is this temperature expressed on the Celsius scale and the Kelvin scale?
    • 40˚C and 375 K
    • 77˚C and 350 K
    • 105˚C and 445 K
    • 395˚C and 605 K36
Answer:

  1. Heat from your hand is absorbed by the ice.
  2. Heat will no longer be transferred from one object to the other.
  3. radiation; convection
  4. Energy is absorbed.
  5. The reactants absorb heat energy from their surroundings.
  6. 77˚C and 350 K






Reference:


Complete Test Preparation for the GED Test 2014 by Steck-Vaughn

GED Science Review: Chemical Reactions

Questions:

Directions: Choose the answer to each question.

Question 1 refers to the passage below.

Atoms of most elements can bond with other atoms. When atoms bond they either transfer or share electrons. If electrons are transferred from one atom to another, each atom takes on a charge; charge atoms are called ions. A bond between ions is an ionic bond. Ionic bond form only between two different elements; the substance that result are ionic compounds. Elements on opposite sides of the periodic table are most likely to join by ionic bonding. Elements closer to each other in the periodic table tend to bond by sharing electrons. Bonds that result when electrons are shared are called covalent bonds. A single covalent bond requires a pair of electrons be shared; one electron comes from each atom. Two or more atoms joined by a covalent bond from a molecule.
Covalent bonds can form between atoms of the same element  or between atoms of two or more different elements. When atoms of different elements are joined by covalent bonds, the result is a covalent compound.

  1. Which situation involves ionic bonding?
    • oxygen and nitrogen gases mixed together in air
    • sugar molecules dissolved in water to form sugar water
    • two hydrogen atoms and an oxygen atom sharing two pairs of electrons
    • calcium giving up two electrons to fluorine atoms to form calcium fluoride

      Questions 2 and 3 refer to the following passage and diagram.

      Compounds can be represented by chemical formulas, structural formulas, and diagrams. For example, the compound methane is shown by the chemical formula CH4. The C stands for carbon, and H stands for hydrogen. The numbers tell you how many atoms are in one molecule of methane. When there is no number, that means there is one atom. Thus, a molecule of methane has one atom of carbon and four atoms of hydrogen.

  2. The structural formula for propane is shown here.



    Which statement is supported by the structural formula for propane?
    • Propane contains nitrogen atoms.
    • The chemical formula for propane is C3H6
    • The chemical formula for propane is C3H8
    • Propane contains more carbon atoms than hydrogen atoms.
  3. When propane burns in air, it reacts with oxygen (O) to form carbon dioxide (CO) and water (HO). Which balanced chemical equation describes this reaction?
    • C3H8 + O2 –> CO2 + H2O
    • C3H8 + 4O2 –> CO2 + 4H2O
    • C3H8 + 5O2 –> 3CO2 + H2O
    • C3H8 + 5O2 –> 3CO2 + 4H2O

      Questions 4 through 6 refer to the following passage and chart.

      Labels on food often list amounts of saturated and unsaturated fats. A saturated molecule is one that contains only single bonds, in which one pair of electrons is shared in each bond. Unsaturated molecules contain other types of bonds, in which more than one pair of electrons are shared.
      A saturated hydrocarbon is saturated with hydrogen. That is, it contains more hydrogen than an unsaturated hydrocarbon with the same number of carbon atoms. One example of a saturated hydrocarbon is ethane, C2H6. An example of an unsaturated molecule is ethane, C2H4. In the unsaturated hydrocarbon ethane, two electrons of one carbon atom are paired with two electrons of another carbon atom, forming a double bond.
      In certain reactions, the double and triple bonds of an unsaturated hydrocarbon can be broken. Hydrogen can then be added to the molecule. A reaction in which hydrogen is added to an unsaturated hydrocarbon is called an addition reaction.

  4. Which element is required for an addition reaction involving hydrocarbons?
    • hydrogen
    • lithium
    • nitrogen
    • oxygen
  5. In contrast to a saturated molecule, what does an unsaturated molecule contain?
    • carbon atoms
    • double bonds
    • hydrogen ions
    • shared electrons
  6. Which conclusion regarding addition reactions is supported by the information presented?
    • Both reactants are hydrocarbons.
    • One reactant is a saturated hydrocarbon.
    • The number of carbon atoms in the original molecule increases.
    • Saturated hydrocarbons are produced from unsaturated hydrocarbons.
  7. The law of conservation of mass states that matter is neither created nor destroyed in normal chemical reactions. In the chemical reaction below, the symbols A and B represent reactants and the symbols C and D represent products. The masses of A, B, and C are given. When the reaction goes to completion, how many grams of substance D will be produced?

    A + B –> C + D
    A = 4.6 g
    B = 7.3 g
    C =  9.2 g
    D = ________ g
  8. In photosynthesis, carbon dioxide and water are converted to glucose and oxygen. The net unbalanced equation for photosynthesis is given. Write the balanced equation.

    CO2 + H2O –> C6H12O6 + O2
    ______________________________________
Answer:

  1. calcium giving up two electrons to fluorine atoms to form calcium fluoride
  2. The chemical formula for propane is C3H8
  3. C3H8 + 5O2 –> 3CO2 + 4H2O
  4. hydrogen
  5. double bonds
  6. Saturated hydrocarbons are produced from unsaturated hydrocarbons.
  7. 2.7
  8. 6CO2 + 6H2O –> C6H12O6 + 602







Reference:


Complete Test Preparation for the GED Test 2014 by Steck-Vaughn

GED Science Review: Properties of Matter

Questions:
Directions: Choose the answer to each question.

Questions 1 through 3 refer to the following paragraph and table.

Solubility is a chemical property referring to the ability of a given substance, the solute, to dissolve in a solvent. Several factors affect the rate at which substances dissolve. Small pieces of a solid dissolve faster than large pieces of the same substance. Smaller pieces have more surface area that is in contact with the solutes dissolve faster in a hot solvent than in a cold solvent. The kinetic theory states that when matter is heated, its particles move faster. Faster-moving solvent particles run into undissolved solute more often. The greater frequency and energy of the collisions help "knock" undissolved solute particles away from each other and spread them throughout the solution. Other factors that affect solubility include pressure, pH, concentration, and state of matter of the solute. For example, gases are more soluble at lower solvent temperatures. The graph shows the solubilities of different solids in water.

  1. How does breaking up a sugar cube that sits on the bottom of a glass of iced tea affect how the sugar dissolves?


    • Unless you stir the tea, breaking up the sugar cube has no effect on how the sugar dissolves.
    • Unless you heat the tea, breaking up the sugar cube has no effect on how the sugar dissolves.
    • Breaking up the sugar cube increases the number of particles and therefore decreases the sugar's solubility.
    • Breaking up the sugar cube increases the sugar's surface area and therefore increases the rate at which it dissolves.
  2. Which variable will increase the rate at which sodium chloride (table salt) dissolves in water?
    • cooling the mixture
    • stirring the mixture
    • using larger pieces of salt
    • changing the solvent to oil

      Directions: Write your answer on a separate sheet of paper.
  3. The data in the graph is based on experimental results. In a paragraph, identify the independent and dependent variables and the control factors in this experiment.

    Questions 4 through 6 refer to the following paragraph and graph.



    If you hold a book in one hand and a comparably sized piece of foam packing material in the other, the book feels heavier. The book feels heavier because it has more mass in the same amount of space. This property of matter is referred to as density. Density is defined as the mass per unit volume of a material. It is an important property—one that, when combined with other properties, helps distinguish one substance from another. In general, gases are less dense that liquids, which are less dense that solids. The bar graph shows the density of some common substances.
  4. which of the following substances is denser than lead?
    • gold
    • iron
    • rust
    • salt
  5. According to the graph, if you melt ice, what is the effect on its density?
    • its density increases.
    • Its density decreases.
    • Its density increases, then decreases.
    • Its density decreases, then increases.
  6. A 50-gram sample of which substance will have the largest volume?
    The ingredients of mixture keep their own properties, and they can be separated from a mixture by physical means as described below.
    • iron
    • lead
    • mercury
    • rust
  7. What happens to the structure of atoms and molecules when a mixture is separated?
    • The atoms and molecules remain in the same combinations before and after a mixture is sorted.
    • The heaviest molecules are unchanged, but lighter molecules can combine to form new substances.
    • The atom and molecules can combine with other atoms to form new substances when a mixture is sorted.
    • The atoms with the smallest diameter stay fixed in place, but larger atoms can combine to form new substances.
  8. What do distillation and extraction have in common?
    • They both involve density.
    • They both involve solutions.
    • They both involve magnetism.
    • They both involve appearance.
  9. petroleum is separated into products such as gasoline and kerosene by heating it to a boiling point and allowing it to cool again. The name of this method is. A dry cleaner used the chemical trichloroethylene to remove a salad dressing stain from a tablecloth. The name of this method is.
Answer:
  1. Breaking up the sugar cube increases the sugar's surface area and therefore increases the rate at which it dissolves.
  2. stirring the mixture
  3. answer depends
  4. gold
  5. its density increases.
  6. The atoms with the smallest diameter stay fixed in place, but larger atoms can combine to form new substances.
  7. The atoms and molecules remain in the same combinations before and after a mixture is sorted.
  8. They both involve solutions.
  9. distillation and extraction







Reference:


Complete Test Preparation for the GED Test 2014 by Steck-Vaughn