The group 17 elements of the periodic table have 7 valence electrons and are highly reactive, with low melting and boiling points. The halogens - including fluorine, chlorine and bromine - have a common tendency to form salts, but they are all of a toxic nature.
https://www.google.com/search?q=what+do+all+halogens+have+in+common&rlz=1C5CHFA_enUS710US710&oq=what+do+all+halogens&aqs=chrome.1.69i57j0l5.6043j0j7&sourceid=chrome&ie=UTF-8
wavelenghts are lengths. they are measured in distances.
Photovoltaic cell is the correct answer ,it converts sunlight into electricity.Hope this helped!
<span>The law of conservation of mass applies to all chemical reaction, so this means that there was equal mass before and after the reaction. However, if the mass has decreased, then it means there has been a loss of substance. The most common cause of this is the liberation of gases from a chemical reaction mixture, the mass of which is not measured by the scale.</span>
Answer:
Electrons are the smallest of the particles that make up an atom, and they carry a negative charge. The number of protons and electrons is equal in a neutral atom. The hydrogen atom, for example, has just one electron and one proton. The uranium atom, on the other hand, has 92 protons, and therefore, 92 electrons.
