Asodium atom (z = 11) contains 11 protons in its nucleus. strictly speaking, the bohr model does not apply, because the neutral atom contains 11 electrons instead of a single electron. however, we can apply the model to the outermost electron as an approximation, provided that we use an effective value zeffective rather than 11 for the number of protons in the nucleus. (a) the ionization energy for the outermost electron in a sodium atom is 5.1 ev. use the bohr model with z = zeffective to calculate a value for zeffective. (b) using z = 11, determine the corresponding value for the radius r of the outermost bohr orbit. (c) using the value calculated for zeffective in part (a), determine the corresponding radius r of the outermost bohr orbit.

Clothing made of several thin layers of fabric with trapped air in between, often called ski clothing, is commonly used in cold climates because it is light, fashionable, and a very effective thermal insulator. so it is no surprise that such clothing has largely replaced thickand heavy old-fashioned coats. (a) consider a jacket made of five layers of 0.1-mm-thick synthetic fabric (k = 0.13 w/m·°c) with 1.5-mm-thick air space (k = 0.026 w/m·°c) between the layers. assuming the inner surface temperature of the jacket to be 28°c and the surface area to be 1.25 m2, determine the rate of heat loss through the jacket when the temperature of the outdoors is 0°c and the heat transfer coefficient at the outer surface is 25 w/m2·°c. (b) what would your response be if the jacket is made of a single layer of 0.5-mm-thick synthetic fabric? what should be the thickness of a wool fabric (k = 0.035 w/m·°c) if the person is to achieve the same level of thermal comfort wearing a thick wool coat instead of a five-layer ski jacket?

Your science teacher brings in a speaker to talk to your class about climate change. during the session, students ask a few questions. which questions are related to the current evidence on climate change

Which of the following list the divisions of the geologic time scale in order from longest to shortest