Latest Physical Science Reviewer 11

1. Which of the following BEST describes temperature?

A. Temperature measures the total energy in something.

B. Temperature measures the kinetic energy in substance.

C. Temperature measures the total kinetic energy contained in an object.

D. Temperature measures the average molecular kinetic energy in substance.

Ans: D. Temperature measures the average molecular kinetic energy in substance.

-Temperature is a measure of the average kinetic energy of the particles of a substance. For instance, if most of the particles of air in your kitchen are moving faster than most of the particles of the bedroom as manifested by smelling quickly what your mother is cooking, then , the temperature of the air in your kitchen is higher than the air in the bedroom.

2. The Earth receives tremendous heat coming from the sun which could be beneficial at one point and harmful to a large extent. Which of the following methods of transferring heat is being illustrated?

A. Conduction

B. Convection

C. Radiation

D. Transduction

Ans : C. Radiation

-The sun’s energy moves through space, then through the Earth’s atmosphere and finally reaches the Earth’s surface. The energy of the sun is called radiation. Radiation is the transfer of heat energy by electromagnetic waves.

3. A reaction takes place endothermically.  Which of the following statements BEST  describes endothermic reactions?

A. The temperature of the system drops.

B. The temperature of the surrounding rises.

C. The temperature of the surrounding drops.

D. The temperature of the surrounding remains the same.

Ans: C. The temperature of the surrounding drops.

-An endothermic reaction is one that absorbs energy from its environment in reaction increases, as the temperature of the reaction increases, the temperature of the surrounding drops.

4. Which of the following statements on specific heat is TRUE?

A. It is an extrinsic  property.

B. It is always equal to the heat capacity.

C. It is the heat capacity per mole of a substance.

D. It is equal to zero when the heat capacity is zero.

Ans: D. It is equal to zero when the heat capacity is zero.

-Specific heat is the amount of the energy to raise the temperature of 1 kilogram of a substance by 1 K. The amount of heat required to raise the temperature by one degree is called heat capacity. If heat capacity is zero, it follows that specific heat is also equal to zero.

5. The entropy usually increase when ________________.

 I. A molecule is broken into two or more smaller molecules

II. A reaction occurs that results in an increase in the number of moles of gas

III.A solid changes to a liquid

IV. A liquid changes to a gas

A. I and II only

B. III and IV only

C. I, II and III only

D. I, II, III, and IV

Ans: D. I, II, III, and IV

-Entropy is a measure of the random activity in a system. I, II, III, and IV are just some factors that affect the amount of entropy in a system. More energy put into a system excites the molecules and the amount of random activity.

6. Change in enthalpy for combustion of fuel is__________.

A. negative

B. positive

C. zero

D. may be negative or positive

Ans: A. negative

-Enthalpy is the sum of the internal energy of the system plus the product of the pressure in the system and its volume. The change in enthalpy for combustion of fuel is negative because the reaction is exothermic.

7. According to the collision theory, when does a chemical reaction occur?

A. If the colliding molecules have energy equal to greater than the activation energy.

B. If the colliding molecules have lesser than the activation energy.

C. If the colliding molecules bouncing apart did not change.

D. If there is no collision among molecules.

Ans: A. If the colliding molecules have energy equal to greater than the activation energy.

-In order for a chemical reaction to take place, the reactants must collide. The collision between the molecules in a chemical reaction must possess enough kinetic energy needed to break the necessary bonds so that new bonds can be formed. The minimum amount of energy required for a chemical reaction to occur is known as the activation energy.

8. Which situation appears to violate the collision theory?

A. The reaction rate increases as temperature increases.

B. The reaction rate decreases as the reaction mixture is cooled.

C. The reaction rate increases as the surface area of the reactants increases.

D. A reaction rate takes more rapidly when the concentration of the reactants is decreased.

Ans: D. A reaction rate takes more rapidly when the concentration of the reactants is decreased.

-In terms of collision theory, increasing the concentration of a reactant increases as the number of collisions between the reacting species per second and therefore increases the transition rate.

9. Which statements is TRUE about catalysts?

A. They increase the rate of reaction by increasing the activation energy.

B. They provide alternative reaction paths with lower activation energies.

C. The amount of catalyst decreases as the reaction progresses.

D. They are used up in the reaction.

Ans: With a catalyst, reactions occur faster and with less energy. It works by providing an alternative mechanism involving a different transition state and lower activation energy. Consequently, molecules collisions have the energy needed to reach the transition state.

10. Milk turns sour in one or two days when left at room temperature and yet can remain unspoiled for two weeks when refrigerated. What explains this?

A. Decrease in temperature speeds up reaction rate.

B. Decrease in temperature slows down reaction rate.

C. Milk becomes less concentrated when placed in refrigerator.

D. Milk becomes more concentrated when placed in refrigerator.

Ans: B. Decrease in temperature slows down reaction rate.

-The use of low temperature to prevent milk and other food from spoiling is based on the fact that the activities of microorganisms can be slowed at temperature above freezing and generally stopped at subfreezing temperatures. The reason is that all metabolic reactions is dependent on temperature.

11. What factor affects sawdust to burn faster than a block of wood?

A. Concentration of reactant

B. Presence of catalyst

C. Surface area of reactant

D. Temperature

Ans: C. Surface area of reactant

-Surface area is the exposed matter of a solid substance. By increasing surface area, there are more collisions per unit. Hence, it increase the reaction rate.

12. Which of the following observation is NOT true whenever a system is in chemical equilibrium?

A. Attainment of equilibrium requires time.

B. The rates of opposing reactions are equal.

C. The products do not change back to reactants.

D. Concentration remain constant at equilibrium even though the opposing reactions are continuing.

Ans: C. The products do not change back to reactants.

-The chemical equilibrium state describes concentrations of reactants and products in a reaction taking place in a closed system, which no longer change with time. It means that the rate of the forward reaction equals the rate of the reverse reaction, such that the concentration of reactants and products remain fairly stable in a chemical reaction. In theory, every forward reaction, there is subsequent reverse reaction.

13. FWhich refers to the recorded observations and measurements in an explanation?

A. Conclusion

B. Data

C. Graph

D. Variables

Ans: B. Data

-Data are factual information or observation which may include appearance or behavior of something in an experimental set-up. Conclusion is the answer or the final decision in a problem. Graphs are diagrams that present the data. Variables are factors that may affect the result of an experiment.

14. How is hypothesis tested?

A. By gathering enough information about the problem

B. By making inferences

C. By conducting experiment

D. By formulating conclusion

Ans: C. By conducting experiment

Hypothesis is a plausible explanation to a problem. It is a simple statement that defines what you think

the outcome of experiment will be. Designing and carrying out an experiment test whether the hypothesis is true or false.

15. Which summarizes a natural occurrence that may be constantly observed given the same conditions which may be expressed in words or in mathematical form?

A. Conclusion

B. Hypothesis

C. Law

D. Theory

Ans: C. Law

A law generalizes a body of observation. At the time it is made, no exceptions have been found. A theory summarizes a hypothesis or group of hypothesis that have been supported with repeated testing. Theories can be disproven while law is universally acceptable. 

16. Which of the following is also known  as paraffin or saturated hydrocarbon?

A. Alkane

B. Alkene

C. Alkyne

D. Cycloalkane

Ans: A. Alkane

-Alkane, also called as paraffin or saturated hydrocarbon, is straight or branched-chain hydrocarbon with only single covalent bonds between the carbon atoms. Alkene contains carbon-carbon double bonds. Alkyne contains carbon-carbon triple bond. Cycloalkane is a closed-chain alkane which is also called cycloparaffin or naphthalene.

17. Which of the following is NOT  true about scientific method?

A. Conclusion is the last step

B. Scientific method may be applied in every life.

C. Scientific method is a systematic way of solving problem.

D. Scientific method is done by following a step-by-step procedure in an exact sequence.

Ans: D. Scientific method is done by following a step-by-step procedure in an exact sequence.

-  While scientific method entails a step-by-step procedure, there are instances that the exact sequence may not be followed yet arrived at the same results.

18. Which of the following are properties of organic compound?

High melting point

Low boiling point

High solubility in water

Non-conductor of electricity

A. I and II

B. I and III

C. II and III

D. II and IV

Ans: D. II and IV

- organic compound are mainly composed of carbon atom. Organic compounds have relatively low melting points and boiling points in comparison to the inorganic compounds of a similar molecular mass. Organic compounds in solution are non- ionic. They are non-conductors of electricity. They don’t disassociate in solutions.

19. What is the classification of an organic compound with the formula CH₃-O-CH₃?

A. Alcohol

B. Ether

C. Phenol

D. Thiol

Ans: B. Ether

-Alcohols are represented by the general formula ROH. Ethers have the general formula ROR’. The groups R and R’ can be derived from saturated, unsaturated, or aromatic hydrocarbon, and for a given either, R and R’ may be alike or different. CH₃-O-CH₃ is known as dimethyl ether. Phenol is a class of compounds that have a hydroxyl group attached to an atomic ring. Thiols or mercaptans are –SH containing compounds.

20. Which apparatus will you use to measure the mass of an irregular solid correctly?

A. Empty beaker

B. Erlenmeyer  flash

C. Graduated cylinder with water

D. Vernier caliper

Ans: C. Graduated cylinder with water

- The mass of an irregular solid can be determined by placing it in a graduated cylinder with wter, then subtracting the initial reading from the final reading. An empty beaker is used to mix and pour liquids. An Erlenmeyer flak is used to mix a large amount of liquid and to pour liquids through small openings. A vernier caliper is used for measuring either the internal or external diameters of tubes, pipes and rods

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