Mg(s) + HCl(aq) → H2(g) + MgCl2(aq) Write a balanced half-reaction equation for the oxidation that occurs.

Answerd. may include all of these are many definitions of bases: the  brønsted-lowry definition of acids and bases says that bases are proton acceptors.the arrhenius definition of acids and bases says that bases increase [oh⁻] in solution (thereby producing oh⁻ ions)the lewis definition of acids and bases says that bases donate electron pairs.therefore, the sensible answer is that a base may include all of the described characteristics.

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged

Ithink it's the third answer

When the electrons fall back down and leave the excited state, energy is re-emitted in the form of a photon. the wavelength (or equivalently, frequency) of the photon is determined by the difference in energy between the two states. these emitted photons form the element's spectrum.