NSCI 100 NSCI100 Pre-Quiz 3 with Answers (UMUC)

NSCI 100 NSCI100  Pre-Quiz 3

1. Which are older, the atoms in the body of an elderly person or those in the body of a baby?
2. Does it make sense to say that a textbook is about 99.9 percent empty space?
3. Since atoms are mostly empty space, why don't objects pass through one another?
4. A beam of protons and a beam of neutrons of the same energy are both harmful to living tissue. The beam of neutrons, however, is less harmful. Why?
5. Which contributes more to an atom's mass: electrons or protons? Which contributes more to an atom's size?
6. If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element?
7. Oxygen atoms are used to make water molecules. Does this mean that oxygen, O2, and water, H2O, have similar properties?
8. The concept of a chemical bond is ________.
9. Which of the following has the greatest number of nonbonding pairs of electrons ?
10. How is it possible for a neutral molecule, such as water, to form an ion?
11. Which of the following elements will most likely not form an ion at all?
12. Take money away from your bank account and the bank will show a negative credit. Take an electron away from an atom, however, and the atom shows up positive. Explain.
13. Which of the following does not describe ionic compounds?
14. Why are ores so valuable?
15. Which of the following substances is pure?
16. A friend argues that if mass were really conserved he would never need to refill his gas tank. What explanation do you offer your friend?
17. The electric charge on all electrons
18. If you strip electrons from an atom, the atom becomes a
19. A difference between electric and gravitational forces is that electric forces include
20. If two protons and two neutrons are removed from the nucleus of an oxygen atom, a nucleus of which element remains?
21. Boron has primarily two isotopes, one with an atomic mass of 11 amu and another with an atomic mass of 10 amu. If the abundance of the boron atom with a mass of 11 amu is 18.9 percent and the abundance of the other isotope is 81.1 percent, what would be the average mass of the boron atom?
22. If an element has 10 protons and 11 neutrons and 10 electrons, which expression correctly identifies the element?
23. What does the following element description actually mean?  - iron-57
24. Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table because
25. Does a shell have to contain electrons in order to exist?
26. What is the valence shell?
27. Is it at all possible for a hydrogen nucleus to emit an alpha particle?
28. Which of the following statements about radiation is true?
29. Which of the following emits more radiation?
30. Which of the following statements best describes a critical mass?
31. Oxygen atoms are used to make water molecules. Does this mean that oxygen, O2, and water, H2O, have similar properties?
32. Many of the macroscopic properties of a compound depend on ________.
33. Which of the following elements has six valence electrons?
34. Why is it so easy for a magnesium atom to lose two electrons?
35. Which of the following would be a negative ion with a single charge?
36. Is an ionic compound an example of a chemical compound, or is a chemical compound an example of an ionic compound?
37. What it the main difference between an ionic and a covalent bond?
38. Which of the following statements is untrue?
39. Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?
40. Which of the following is the strongest?
41. What is the difference between a compound and a mixture?
42. A combination of two or more substances in which they no longer retain their chemical properties is called a(n) ________.
43. Why can't the elements of a compound be separated from one another by physical means?
44. Classify the following as element, compound, or mixture, and justify your classifications: table salt, stainless steel, table sugar, aluminum, ice.
45. Which has the most atoms?