Which of the following measurements contains two significant figures? a. 0.00300 l b. 0.00303 l c. 0.00033 l d. 0.00330 l

Which of the following is essential for a theory to become widely accepted within the scientific community? (2 points) 2points a a theory must include a valid scientific model. b a theory must be supported by many different experiments. c a theory is an educated guess based on multiple observations. d a theory must change over time regardless of the scientific data. multiple choice question 2 which of the following best explains why the atomic theory changed over the past 200 years? (2 points) 2points a the theory was terribly flawed. b few people believed it was correct. c the atomic model was incomplete. d new experiments led to revised ideas. multiple choice question 3 which is true of an effective scientific model? (2 points) 2points a it seldom needs refining because of its detailed accuracy. b it clearly depicts the particular set of characteristics being modeled. c it is an exact visual representation of the characteristics being modeled. d it is the same size and color as the scientific phenomena being demonstrated. multiple choice question 4 which is true about models in science? (2 points) 2points a models are accurate enough for the phenomena they represent. b models only present macroscopic versions of the submicroscopic. c models explain phenomena but are not good for predicting events. d models are used throughout science although they are not always accurate. long answer question 5 describe at least two changes that occurred to the atomic model over time, along with the experimental evidence that made these changes necessary. (4 points) 4points 1000 word(s) left multiple choice question 6 modern atomic theory states that atoms are neutral. how is this neutrality achieved in atoms? (2 points) 2points a having more neutrons than protons or electrons b having equal numbers of protons and electrons c having fewer neutrons than protons or electrons d having equal numbers of protons and neutrons multiple choice question 7 which subatomic particles exist in orbital energy levels, or shells? (2 points) 2points a electrons b ions c protons d neutrons multiple choice question 8 a neutral atom of sodium (na) has an atomic number of 11 and a mass number of 23. how many neutrons would be found in the nucleus of this atom of sodium? (3 points) 3points a 34 b 23 c 12 d 11 multiple choice question 9 the atomic number of magnesium (mg) is 12. this is also the number of which of the following? (2 points) 2points a neutrons b protons c atomic mass d ionic charge multiple choice question 10 two atoms that have the same atomic number but different mass numbers are called (2 points) 2points a compounds. b ions. c isotopes. d radicals. multiple choice question 11 the most common isotope of nitrogen is nitrogen-14, or 14n. which of the following atoms has the same number of neutrons as 14n? (2 points) 2points a 16o b 15n c 14p d 13c multiple choice question 12 the atomic and mass numbers for four different atoms are given below. which two are isotopes of the same element? (2 points) atom atomic number mass number a 100 257 b 101 257 c 101 260 d 102 259 2points a a and b b b and c c b and d d c and d multiple choice question 13 a newly discovered element, z, has two naturally occurring isotopes. 93.5 percent of the sample is an isotope with a mass of 268.9 u, and 6.5 percent of the sample is an isotope with a mass of 269.9 u. what is the weighted average atomic mass for this element? (2 points) 2points a 268.5 u b 269.0 u c 269.4 u d 269.8 u multiple choice question 14 if a chemist has 2.3 moles of arsenic (as) that has a molar mass of 74.92 g/mol, which would be the best way to find out how many atoms of arsenic are in the sample? (2 points) 2points a multiply 2.3 by avogadro's number. b divide 2.3 by avogadro's number. c multiply 2.3 by the molar mass of arsenic. d divide 2.3 by the molar mass of arsenic.