TX PACT 4-8 CORE (790) question n answers

TX PACT 4-8 CORE (790)How many SFs in 0.? - correct answer 8 SFs: Addition and Subtraction Rules - correct answer answer has the same # decimal places as numeral w/the smallest # of decimal places. EX: 1063.02 + 12.5 = 1075.5 SFs: Multiplication/Division Rules - correct answer answer has the same # of SFs as numeral with smallest # of SFs. EX: 1063.02 x 12.5 = 13287.75 => 1.33 x 10^4 Define: Hypothesis, Theory, and Scientific Law - correct answer Hypothesis: testable prediction based on observations (educated guess) Theory: proposed explanation, based on evidence, that may or may not be testable. (educated explanation on why something happens) Scientific Law: proven and documented description of observations surrounding phenomena (states what will happen not why) *theories do not become laws independent variable - correct answer The experimental factor that is manipulated by the scientist; the variable whose effect is being studied. (usually on x-axis) dependent variable - correct answer The measurable factor; the variable that may change in response to (or depend on) manipulations of the independent variable. Precision - correct answer a measure of how close a series of measurements are to one another Accuracy - correct answer how close a measurement is to the true value Negative feedback - correct answer A type of regulation that responds to a change in conditions by initiating responses that will counteract the change or correct the system back to original state. Maintains a steady state (homeostasis). EX: body temperature Positive feedback - correct answer A type of regulation that responds to a change in conditions by initiating responses that will amplify the change. Takes organism away from a steady state. EX: Global warming or contractions Matter - correct answer Anything that has mass and takes up space (made up of atoms) Ground state of atoms - correct answer lowest energy, most stable electron configuration Neutrons - correct answer neutral charge; mass # - atomic # (protons) Quantum Model - correct answer current atomic model in which e- move in waves around nucleus (w/ uncertain positions in an e- cloud) Molecules vs. Compounds - correct answer Molecules: Groups of two or more atoms held together by chemical bonds Ex: O2 & consist of compounds too Compounds: 2 or more DIFF. elements held by ionic or molecular bonds Ex: H2O, NaCl, etc.. Isotopes - correct answer atoms w/ same # of protons, but diff. # of neutrons Radioactivity - correct answer The spontaneous nuclear emission of radiation by an unstable atomic nucleus, which changes # of protons (identity of element)