Which of the following correctly gives the best coefficients for the reaction below? Zn + HCl → ZnCl2 + H2

2, 4, 2, 4

1, 2, 1, 4

1, 2, 1, 1

2, 1, 1 ,1

1, 1, 2, 1

Thank you for the help in advance.

If you chip a tooth, most likely you will go to the dentist to have the missing material filled in. currently the material used to fill in teeth is a polymer that is flexible when put in, yet is hardened to the strength of a tooth after irradiation with blue light at a wavelength of 461 nm. what is the energy in joules for a photon of light at this wavelength?

Answer explain why it is not possible to deduce a complete order of reactivity.

What best discribes the relationship between wavelength and frequency in a electromagnetic wave