Rebecca conducted a study on the effects of sleep deprivation for twelfth-graders during midterm exams. she followed two groups of five students each. after two grading periods, she turned in the data she collected. which two steps in the scientific process were left out of her study? a. conclusion and communication b. problem and hypothesis c. experimentation and summation d. research and analysis

Asample of silver (with work function ? = 4.52 ev) is exposed to an ultraviolet light source (? = 200 nm), which results in the ejection of photoelectrons. what changes will be observed if: silver is replaced with copper (? = 5.10 ev) more photoelectrons ejected no photoelectrons are emitted fewer photoelectrons ejected more energetic photoelectrons (on average) less energetic photoelectrons (on average)

What amount of heat is exchanged when 106.2 grams of substance y goes from a liquid at 35 degrees celsius to a solid at the same temperature? melting point of substance y = 35 degrees c; δhvaporization = 3.67 j/mol; δhfusion = 3.30 j/mol. mwsubstance y = 28.22 g/mol. −12.4 j −3.51 x 102 j 1.24 x 101 j 351 j

What is the difference between covalent bonds and ionic bonds? covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms. covalent bonds involve the transfer of electrons between charged atoms; ionic bonds involve the sharing of electrons between atoms. covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms. covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between charged atoms.