H. Physical Science 2nd Semester Review Short Answer 1. What is the purpose of balancing a chemical equation?
2. A student balanced the chemical equation Mg + O2 ® MgO by writing Mg + O2 ® MgO2. Was the equation balanced correctly? Explain your answer. If the equation was not balanced correctly, write the correctly balanced equation.
3. How many moles of nitrogen are contained in 1.61 ´ 1024 atoms of nitrogen?
4. How many grams of Mn are in 4.0 mol of the element?
5. In a decomposition reaction, a compound is broken down into two or more simpler substances. Explain why the term compound is used to refer to the reactant and the term substances is used to refer to the products.
6. Magnesium will replace silver in a compound. What are the products of a single-replacement reaction between magnesium and silver nitrate?
7. What are the products of a neutralization reaction?
8. How did the physicist Becquerel first observe the effects of nuclear decay?
9. What particle will balance the following nuclear equation?
Pa ® U + ?
10. A sample of uranium-238 is heated from room temperature to 55°C. How will increasing the temperature of the sample affect the half-life of the radioisotope?
Figure 11-1 11. From which frame of reference in Figure 11-1 does the tree appear to be in motion?
12. What is the significance of the slope in a distance-time graph?
13. What types of changes in motion cause acceleration?
14. In the equation for acceleration, , how can you describe acceleration if the numerator is negative?
15. What information does the slope of a speed-time graph provide?
Figure 12-1 16. Figure 12-1 shows the paths followed by three balls. Each ball started moving at the same time. Ball A was dropped and balls B and C were thrown sideways. Compare the times for each ball to reach the ground.
17. How are the size and direction of action-reaction forces are related?
18. What type of mechanical wave is produced by pushing sharply on the end of a spring toy?
19. In what unit is wave frequency measured?
20. Suppose two waves meet and temporarily cancel each other out. How would you describe the interference?
21. How do the frequencies of ultrasound compare to the frequencies that people normally hear?
22. What is the Doppler effect?
23. What is a basic difference between electromagnetic waves and sound waves?
24. Which type of electromagnetic wave has the longest wavelength and lowest frequency?
25. What two factors influence the color of an object?
26. What is the usual method of graphically analyzing how light rays behave when they strike mirrors or pass through lenses?
27. If you are standing 1 meter in front of a plane mirror, how far does your image appear to be behind the mirror?
28. What are three ways that a charge can be transferred?
29. What is the difference between direct current and alternating current?
30. What is the voltage in a circuit if the current is 3 amps and the resistance is 3 ohms? Explain your answer.
31. If the voltage is 90 volts and the resistance is 30 ohms, what is the current? Explain your answer.