Q: Answer the following question given this paragraph: Electron Shells and the Bohr Model It should be stressed that there is a connection between the number of protons in an element, the atomic number that distinguishes one element from another, and the number of electrons it has. In all electrically neutral atoms, the number of electrons is the same as the number of protons. Thus, each element, at least when electrically neutral, has a characteristic number of electrons equal to its atomic number. An early model of the atom was developed in 1913 by Danish scientist Niels Bohr (18851962). The Bohr model shows the atom as a central nucleus containing protons and neutrons, with the electrons in circular orbitals at specific distances from the nucleus, as illustrated in Figure 2.6. These orbits form electron shells or energy levels, which are a way of visualizing the number of electrons in the outermost shells. These energy levels are designated by a number and the symbol "n. " For example, 1n represents the first energy level located closest to the nucleus. Q: What is the number of electrons equal to in every electrically neutral atom? A:

OPTIONS:
- Electrons
- molecules
- nucleus
- protons

A: protons

Q: Answer the following question given this paragraph: Metals will typically lose electrons to achieve stability, while non-metals typically gain electrons to achieve stability. Two atoms or ions with the same number of electrons are referred to as isoelectronic . Q: What do metals typically lose to achieve stability? A:

OPTIONS:
- ions
- atoms
- molecules
- electrons

A: electrons

Q: Answer the following question given this paragraph: Careful farming helps to keep up soil quality each season. One way is to plant different crops each year. Another is to alternate the crops planted in each row of the field. These techniques preserve and replenish soil nutrients. Planting nutrient rich cover crops helps the soil. Planting trees as windbreaks, plowing along contours of a field, or building terraces into steeper slopes all help to hold soil in place ( Figure below ). No-till or low-till farming disturbs the ground as little as possible during planting. Q: What is the purpose of utilizing careful farming practices such as rotating crops or planting nutrient rich crops? A:

OPTIONS:
- improve sediment quality
- improve photosynthesis quality
- improve soil texture
- improve soil quality

A: improve soil quality

Q: Answer the following question given this paragraph: An oxygen molecule has two nonpolar bonds. This is called a double bond. The two oxygen atoms attract equally the four shared electrons. Q: How many nonpolar bonds does an oxygen molecule have? A:

OPTIONS:
- 5
- 7
- 3
- 2

A:
2