Pls answer only if you know, or I'll report your An unknown element X reacts in air to form its oxide Y. This Y dissolves in water which turns blue litmus into red.
Predict the nature of oxide ‘Y’ and tell whether ‘X’ is a metal or a non-metal? Name two elements that behave like ‘X’.

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?