A student stands in a school hallway. A wall separates a classroom from the student. The student in the hallway cannot see inside the classroom but hears noises from within the classroom. Which of these best explains why the student hears the noises but cannot see into the classroom?
Sound waves are absorbed by the wall, and visible light waves are transmitted through the wall.
Sound waves are transmitted through the wall, and visible light waves are reflected by the wall.
Sound waves are reflected by the wall, and visible light waves are refracted by the wall.
Sound waves are reflected by the wall, and visible light waves are absorbed by the wall.

Which statement best describes the oxidation numbers of the atoms found in magnesium chloride? a. magnesium has a 2- oxidation number and chlorine has a 1+ oxidation number. b. magnesium has a 2- oxidation number and chlorine has a 2+ oxidation number. c. magnesium has a 2+ oxidation number and chlorine has a 1- oxidation number. d. magnesium has a 1+ oxidation number and chlorine has a 1- oxidation number.

Using the periodic table, complete the table to describe each atom. type in your answers.a ? b? c? d? e? f?

Problem page combustion of hydrocarbons such as pentane ( c5 h12 ) produces carbon dioxide, a "greenhouse gas." greenhouse gases in the earth's atmosphere can trap the sun's heat, raising the average temperature of the earth. for this reason there has been a great deal of international discussion about whether to regulate the production of carbon dioxide.(a) write a balanced chemical equation, including physical state symbols, for the combustion of liquid pentane into gaseous carbon dioxide and gaseous water. (b) suppose 0.350 kg of pentane are burned in air at a pressure of exactly 1 atm and a temperature of 20.0 degree c. calculate the volume of carbon dioxide gas that is produced.be sure your answer has the correct number of significant digits.