Description QUESTION 1 Which of the following is an accurate description of a theory? a well-test ...
Description QUESTION 1 Which of the following is an accurate description of a theory? a well-tested explanation for how something works. an observation made over and over again. someone's idea about how something works. easily proved wrong and therefore cannot be trusted in science. 3 points Save Answer QUESTION 2 Which of following statements is true about scientific knowledge? Scientific ideas are not subject to change, and so knowledge stays the same. Scientific knowledge is constantly evolving as new observations are made. While scientific knowledge increases over time, old knowledge never changes. Theories can change frequently, but scientific knowledge is absolute. 3 points Save Answer QUESTION 3 Which of the following is an example of pure research? Determining the causes of dementia in elderly people. Creating robots to walk on the surface of Mars. Colliding subatomic particles at high speeds to see what they form. Working with alloys to determine the lightest carbon fiber composition for armor. 3 points Save Answer QUESTION 4 Which of the following institutions employs scientists? Hospitals Universities Corporations All of the above 3 points Save Answer QUESTION 5 If the flame of a Bunsen burner should accidentally go out, a student should immediately run over to the teacher and inform him/her. TRUE FALSE 2 points Save Answer QUESTION 6 In terms of eye safety in the lab: Students do not need to wear safety goggles if they already have prescription glasses on. Students need to wear safety goggles at all times, regardless if they have prescription glasses or not. Students only need to wear safety goggles if they do not have their own prescription glasses or if they have contacts. Goggles only need to be worn if the chemicals used in a lab are liquids or solutions. 3 points Save Answer QUESTION 7 You observe that a liquid has decreased volume by 23.4 milliliters (mL) during the duration of an experiment. What is this type of observation? quantitative qualitative indirect observation a physical change 3 points Save Answer QUESTION 8 It is equally accurate to measure volumes with a beaker as with a graduated cylinder. TRUE FALSE 2 points Save Answer QUESTION 9 When measuring the volume of a liquid in a graduated cylinder, you should raise the cylinder up to eye level to read the meniscus more accurately. TRUE FALSE 2 points Save Answer QUESTION 10 To accurately measure the volume of a typical liquid in a graduated cylinder, what should you do? look at the bottom part of the meniscus look at the top part of the meniscus average the top and bottom parts of the meniscus ignore the meniscus and determine which mL line the liquid is closest to 3 points Save Answer QUESTION 11 To accurately measure out 35 milliliters of liquid, you should use: a 10-mL glass pipette several times a 50-mL beaker a 25-mL graduated cylinder two times a 50-mL graduated cylinder one time 3 points Save Answer QUESTION 12 Two groups complete an experiment requiring the mass measurement to be repeated three times in the experiment. Group I selects a single member of the group to measure the mass. Group II allows any person of the group to measure the mass once, so they will be done more quickly. At the end of the experiment, the results for group I are closer to the actual than the results of group II. Explain why this might be. Press Tab to enter the content editor. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). Path: pWords:0 5 points Save Answer QUESTION 13 Which of the following would be considered the most heterogeneous mixture? oil/vinegar salad dressing pasteurized milk vinegar olive oil 3 points Save Answer QUESTION 14 Which of the following pairs forms a homogenous mixture after being mixed together? sand and water salt and water oil and water oil and vinegar 3 points Save Answer QUESTION 15 Which of the following is an example of a physical change? Rusting bicycle chain Melting butter Fireworks exploding Baking a cake 3 points Save Answer QUESTION 16 Which of the following is an example of a physical change? Separating sand from gravel Baking a pie Burning a piece of paper Rusting 3 points Save Answer QUESTION 17 Of the following examples, select those that represent a chemical change.I. Water freezing and changing into iceII. Leaves changing color in the fallIII. Mixing lemonade mix powder with waterIV. Milk going sour II, III, IV I, II, III, IV II, IV I, II 3 points Save Answer QUESTION 18 Which of the following is an example of a chemical property? Flammability Boiling point Density Elasticity 3 points Save Answer QUESTION 19 A mixture of sand and iron filings can be separated into its individual components by using a magnet. TRUE FALSE 2 points Save Answer QUESTION 20 Which of the following is NOT a method used to physically separate components in a mixture? chromatography sublimation distillation precipitation 3 points Save Answer QUESTION 21 The best way to separate ethanol from its solution in water is to use which of the following? chromatography precipitation distillation filtration 3 points Save Answer QUESTION 22 The standard (Bohr) model of the atom shows that: a positively charged nucleus has negatively charged particles surrounding it a neutrally charged nucleus has neutrally charge particles encompassing it a negatively charged nucleus has positively charged particles encompassing it a positively charged nucleus has positive or negatively charged particles encompassing it 3 points Save Answer QUESTION 23 An atom has no electrical charge because: its subatomic particles have no electrical charges the positively charged neutrons cancel out the negatively charged electrons the negatively charged neutrons cancel out the positively charged protons there are as many positively charged protons as negatively charged electrons 3 points Save Answer QUESTION 24 The atomic number represents the total number of protons and neutrons in an atom. TRUE FALSE 2 points Save Answer QUESTION 25 Electrons exist only outside of the nucleus. TRUE FALSE 2 points Save Answer QUESTION 26 Pick the correct statement for the following isotope: 42Ca 42 is the mass number and 20 is the atomic number. 42 is the number of neutrons and 20 is the number of protons. 42 is the number of protons and 20 is the number of electrons. 42 is the atomic number and 20 is the number of neutrons. 3 points Save Answer QUESTION 27 In structure, the standard (Bohr) model of the atom is most similar to plum pudding our solar system chocolate chip cookie dough the Milky Way galaxy 3 points Save Answer QUESTION 28 Most of the volume of an atom is contained: in the protons in the nucleus in the neutrons in the empty space around the nucleus 3 points Save Answer QUESTION 29 In comparing two isotopes of the same element, the atomic number: changes to reflect the number of protons. changes to reflect the new mass number. changes to reflect the number of new neutrons. stays the same. 3 points Save Answer QUESTION 30 If the number of protons for an element changes, then: the element turns into an isotope the element becomes a different element the number of electrons for that element changes as well the number of neutrons changes as well 3 points Save Answer QUESTION 31 Use the information for the isotopes of element X to calculate the average atomic mass of X, and identify the element. Isotope Abundance Mass (amu) 35X 75.77% 34.969 37X 24.23% 36.965 Press Tab to enter the content editor. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). Path: pWords:0 5 points Save Answer QUESTION 32 Which of the following statements about subatomic particles best characterizes protons? positive charge, heavy, found in the nucleus of an atom no charge, heavy, found in the nucleus of an atom negative charge, light, circling the nucleus of an atom no charge, light, circling the nucleus of an atom 3 points Save Answer QUESTION 33 Henry Moseley determined that, with a few exceptions, the order of increasing atomic number is the same as increasing atomic mass. TRUE FALSE 2 points Save Answer QUESTION 34 Who was the first person to organize the elements so that properties of undiscovered elements could be predicted? J.W. Dobereiner Dmitri Mendeleev JJ Thomson Ernest Rutherford 3 points Save Answer QUESTION 35 Generally, when going from left to right across a period on the periodic table: atomic radii decrease ionic radii increase electronegativity decreases valence electron number decreases 3 points Save Answer QUESTION 36 In the periodic table, alkali metals are situated: At the extreme left side. At the extreme right side. Towards the middle of the periodic table. Directly next to the right of the stair steps/metalloids. 3 points Save Answer QUESTION 37 Generally, when going down columns 1 or 2 of the periodic table, the reactivity of elements: increases decreases remains the same except for noble gases remains the same except for halogens 3 points Save Answer QUESTION 38 Which of the following classifications is NOT correct? Group 1 and Group 2 - Metals Group 7 - Halogens Group 8 - Noble Gases Group 5 - Metalloids 3 points Save Answer QUESTION 39 Which of the following classifications is NOT correct? Noble gases - 8 valence electrons Halogens - 6 valence electrons Transition metals - number of valence electrons varies Alkali Rare Earth metals - 2 valence electrons 3 points Save Answer QUESTION 40 The chemical symbol for lead is La. TRUE FALSE
