Answers edited by Priya

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• A sample of hydrogen has an initial temperature of 50.° C. When the temperature is lowered to -5.0° C, the volume of hydrogen becomes 212 cm3. What was the initial volume of the hydrogen in dm3?
  
• How is mass number related to isotopes?
  
• A sample of O2 under 2.00 atm occupies 500 ml at 25.0˚C. What temperature will be needed to produce a pressure of 4.00 atm?
  
• What is a reaction rate?
  
• How can the periodic table be used to predict the properties of the elements?
  
• Question #3c8f0
  
• What is an example of a percent composition practice problem?
  
• What is half-life?
  
• What does a buffer do in a solution?
  
• What causes gas pressure (in terms of kinetic theory)?
  
• Question #f7c86
  
• How many moles of sodium hydroxide are needed to neutralize 1 mole of phosphoric acid?
  
• How many hybrid orbitals are present in the molecule PCl5?
  
• Question #6b0c2
  
• How does solubility change with temperature changes?
  
• What is an atom?
  
• How can atomic emission spectra be useful?
  
• How does the ideal gas law differ from the combined gas law?
  
• What is the oxidation state of chromium in Cr(H2O)6 (3+)?
  
• If 500 mL of HCl gas at 300 K and 100 kPa dissolved in pure water requires 12.50 mL of the NaOH solution to neutralize in a titration experiment, what is the concentration of the NaOH solution?
  
• How can molarity and osmolarity be calculated from m/v?
  
• Why are all spontaneous processes not exothermic?
  
• Did Rutherford's gold foil experiment change the view of the atom?
  
• How does ion size affect conductivity?
  
• What is the total gas pressure in a sealed flask that contains oxygen at a partial pressure of 0.41 atm and a water vapor at a partial pressure of 0.58 atm?
  
• Question #d7f86
  
• What is linear mass density?
  
• If 100.0 g of a radioactive isotope that has a half life of 25 years, identify the amount of that isotope that will remain after 100 years?
  
• How does counter-current mechanism in the Loop of Henle work?
  
• How can I classify metalloids?
  
• Question #c5be6
  
• Question #14194
  
• Do relative osmolarities relate to water movement?
  
• How can I calculate percent concentration by mass?
  
• Question #c0638
  
• How do valence electrons form bonds?
  
• How are atomic spectra used?
  
• Question #25b41
  
• How do oxidation numbers relate to electron configuration?
  
• Is heat capacity larger for polymers?
  
• What is the balanced equation for combustions of propane gas that yields carbon dioxide and water?
  
• What do you mean by the ground state of a system?
  
• How does Boyle's law relate to breathing?
  
• Question #2f835
  
• What is an example of a VSEPR model practice problem?
  
• How does multigrade oil work?
  
• How does the collision theory explain how chemical reactions occur?
  
• What temperature scale does China use?
  
• What is a formula that demonstrates the law of multiple proportions?
  
• Question #3e282
  
• What's the mole number?
  
• How can a galvanic cell become an electrolytic cell?
  
• How do you determine the correct subscripts in a chemical formula?
  
• Does the Heisenberg uncertainty principle apply to cars and airplanes?
  
• What is a linear regression?
  
• A sample of carbon is placed in a rigid 1.50 L flask. Dinitrogen monoxide is added and the flask heated to 800C. When the system reached equilibrium the partial pressure of the carbon dioxide is found to be 0.030 atm and the partial pressure of the dinitrogen monoxide to be 1.48 atm. What is the value of the equilibrium constant, Kp for the system at 800C?
  
• A certain sample of gas has a volume of 0.452 L measured at 87°C and 0.620 atm. What is its volume at 1 atm and 0°C?
  
• What is a polyatomic ion?
  
• What covalent bonds are in sulfamic acid and water?
  
• How does temperature affect changes of state?
  
• How many bonding orbitals are in Silicon Tetraflouride, or #SiF_4#?
  
• How many grams of NaCl are produced when 80.0 grams of O2 are produced? 2 NaClO3 ---> 2 NaCl + 3 O2
  
• What is osmolarity of body fluids?
  
• How do you find the molality of an unknown solution?
  
• Why does neutralization occur?
  
• What amount of ice must be added to 540.0 g of water at 25.0 °C to cool the water to 0.0 °C and have no ice?
  
• How can I calculate the molecular weight of the empirical formula?
  
• Question #94985
  
• A sample of carbon is placed in a rigid 1.50 L flask. Dinitrogen monoxide is added and the flask heated to 800C. When the system reached equilibrium the partial pressure of the carbon dioxide is found to be 0.030 atm and the partial pressure of the dinitrogen monoxide to be 1.48 atm. What is the partial pressure of nitrogen in the mixture.
  
• Calculate the number of joules given off when 32.0 grams of steam cools from 110.0 °C to ice at -40.0 °C.
  
• Why are closed shells more stable?
  
• Question #d7f4a
  
• How is nuclear stability related to the neutron-proton ratio?
  
• How did Tycho Brahe and Kepler employ the scientific method?
  
• Why is the rate of reaction fastest at the beginning?
  
• What is a reaction rate constant?
  
• What temperature scale does Australia use?
  
• What sort of radiation can cause genetic mutations?
  
• How many valence electrons does bromine have?
  
• Question #f6476
  
• Is the source of the sun's energy nuclear fusion or nuclear fission?
  
• Is CH3CO2H a dipole dipole?
  
• What is the chemical equation for cesium + iodine ---> cesium iodide?
  
• How do covalent bonds dissolve in water?
  
• How do you calculate the number of days required for 3/4 of a given amount of nuclide to decay if the half-life is 18 point 72 days?
  
• Question #42ee6
  
• Question #bb7b1
  
• What are the limitations of the octet rule?
  
• Why are atomic masses of most of the elements fractional?
  
• How does a galvanic cell differ from an electrolytic cell?
  
• The temperature measured in an experiment was #"64.9"^@"C"#. The theoretical temperature is #"55.0"^@"C"#. What is the percent error?
  
• Does positron decay result in nuclear transmutation?
  
• How can a chemical change be sped up?
  
• Question #bc74d
  
• In a double bond how many pi and sigma bonds are there?
  
• How do you determine how much of the excess reactant is left over? Also, how do you determine how much MORE of the limiting reagent would you need to use up the excess?
  
• Question #fee47
  
• How many atomic orbitals are there in a p subshell?
  
• What covalent compound is N2S?
  
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