Which substance will most likely ionize when it is dissolved in water? HBr CaBr_(2) MgCl_(2) KCl

ll the substances listed will ionize when dissolved in water, as they are all ionic compounds. However, $HBr$ is a strong acid and will completely ionize in water to form $H^+$ and $Br^-$ ions. The other substances ($CaBr_2$, $MgCl_2$, and $KCl$) are salts that also dissociate into their respective ions, but $HBr$ is specifically noted for its complete ionization as an acid. Therefore, $HBr$ is the substance that will most likely ionize when dissolved in water.