TX PACT 4 -8 CORE (790) QUESTIONS AND ANSWERS ALREADY PASSED How many SFs in 0.010025600? - Answer ✔️✔️-8 SFs: Addition and Subtraction Rules - 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 - 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 - Answer ✔️✔️-Hypothesis: testable prediction based on observations (educated guess) Theory: propo sed 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 n ot become laws independent variable - Answer ✔️✔️-The experimental factor that is manipulated by the scientist; the variable whose effect is being studied. (usually on x -axis) dependent variable - Answer ✔️✔️-The measurable factor; the variable that may ch ange in response to (or depend on) manipulations of the independent variable. Precision - Answer ✔️✔️-a measure of how close a series of measurements are to one another Accuracy - Answer ✔️✔️-how close a measurement is to the true value Negative feedback - 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 - 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 - Answer ✔️✔️-Anything that has mass and ta kes up space (made up of atoms) Ground state of atoms - Answer ✔️✔️-lowest energy, most stable electron configuration Neutrons - Answer ✔️✔️-neutral charge; mass # - atomic # (protons) Quantum Model - Answer ✔️✔️-current atomic model in which e - move in wa ves around nucleus (w/ uncertain positions in an e - cloud) Molecules vs. Compounds - 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 - Answer ✔️✔️-atoms w/ same # of protons, but diff. # of neutrons Radioactivity - Answer ✔️✔️-The spontaneous nuclear emission of radiation by an unstable atomic nucleus, which changes # of protons (identity of element) Alpha Decay - Answer ✔️✔️-Radioactive decay in which an atom emits an alpha particle (w/ 2P and 2N). This decreases the atomic # by 2 and the mass number by 4. emission of helium -4 nucleus Beta Decay - Answer ✔️✔️-radioactive decay in which neutron changes into proton by emitting an e - and neutrino. This increases atomic # by 1 and mass stays the same. emission of an electron or a positron Gamma Decay - Answer ✔️✔️-radioactive decay by emission of a gamma ray; atomic # and mass # do not change. carbon dating - Answer ✔️✔️-uses half life to approximate age of fossils. solute - Answer ✔️✔️-the substance tha t is dissolved in solvent "pUT the solUTe in the solvent" density - Answer ✔️✔️-mass/volume Kinetic Molecular Theory of Matter - Answer ✔️✔️-all matter is constantly in motion - KE and speed increases as temp. increases Wind turbine energy transformation - Answer ✔️✔️-kinetic (wind moves motor) to mechanical (generator) strongest to weakest bonds - Answer ✔️✔️-covalent, ionic, hydrogen types of bonds - Answer ✔️✔️-- covalent: e - are shared b/t 2 atoms (usually NM) - ionic: oppositely charged ion attractio n - one atom loses e -, other accepts [one M (+), one NM ( -)] - metallic: 2 metal atoms - hydrogen: weak bonds, easily breakable states of matter - Answer ✔️✔️-solid: rigid, fixed shape & volume liquid: fixed volume gas: compressible during a phase chang e, temp. is constant until change is complete and matter is conserved Combination Rxn - Answer ✔️✔️-A+B -->AB Decomposition Rxn - Answer ✔️✔️-AB --> A + B Single Replacement Rxn - Answer ✔️✔️-One element/molecule replaces another A + BC --> B + AC Double Replacement Rxn - Answer ✔️✔️-AB + CD --> AD + CB Combustion Rxn - Answer ✔️✔️-C reacts with O 2, burns, and produces CO 2 and H 2O in the process. Redox Rxn - Answer ✔️✔️-transfer of electrons that changes charge (oxidation #) of atom in the reaction Oxidation - Answer ✔️✔️-OIL = losing e - 0 --> 1+ b/c lost an e - to make + charge Reduction - Answer ✔️✔️-RIG = gaining e - 1+ --> 0 b/c gained an e - to make neutral charge Energy - Answer ✔️✔️-ability to create heat or do work; always conserved Thermal Ene rgy - Answer ✔️✔️-The total internal energy of all of the particles motion in a substance -- transfers heat Heat Energy - Answer ✔️✔️-transfer of thermal energy - energy transferred from hot to cold Laws of Thermodynamics - Answer ✔️✔️-- Zeroth: 2 bodies a re in thermal equil. w/ 3rd body, then they are all in thermal equil. (have the same temp.) - 1st: Internal Energy (U) = Heat (Q) - Work
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