An erbium YAG laser is used in dentistry to remove cavities often without the need of an anesthetic.  The ER:YAG laser has a wavelength of 2940 nm.  What is the energy of one photon of this light?

A solution of AgNO3is titrated with 66.13 mL of 0.04155 M CaCl2 .  Which of the following statements are true?   silver chloride is a precipitate no reaction happens calcium nitrate is a precipitate   When the precipitate is dried and weighed, how much precipitate would there be?    there is no precipitate 0.7876 g 0.3938 g 0.4509 g

Which of the following statements is/are true?  The electron configuration of arsenic (As) is [Ar]4s24d103p3 The electron configuration of silicon (Si) is [Ne]3s23p2 The electron configuration of germanium (Ge) is [Ar]4s23d104p2  

Calculate the energy of a photon emitted by a hydrogen atom when the electron falls from the n=14 energy level to the n=5 energy level.

Calculate the energy of a photon emitted by a hydrogen atom when the electron falls from the n=15 energy level to the n=5 energy level.

Which of the following when mixed with lithium sulfate (Li2SO4) will produce a precipitate?  SrI2 Fe(NO3)2 Pb(C2H2O2)2

A saline solution is prepared by mixing 21.384 g of NaCl into enough water to make 220.00 mL of solution.  325.00 mL of water is then added to the first solution.  What is the concentration of the final solution?

Phosphoric acid, H3PO4 is titrated with NaOH.  When the equation is balanced, what is the sum of all of the coefficients?

A researcher runs an experiment that produces 113.4 g of aluminum sulfate when adding 23.7 g of aluminum to excess sulfuric acid according the the following equations.  What is the percent yield of the reaction?  2Al(s) + 3H2SO4(aq) 

Which of the following statements is/are true?  The electron configuration of sulfur (S) is [Ne]3s23p4 The electron configuration of tin (Sn) is [Kr]5s24d105p2 The electron configuration of antimony (Sb) is [Kr]5s25d104d3