Then as the electrons in the atoms fall back down, they emit electromagnetic radiation (light). The amount of light emitted at different wavelengths, called the emission spectrum, is shown for a discharge tube filled with hydrogen gas in Figure 12.6 below.
Sodium is a metal and bromine is a nonmetal so they form an ionic compound
nonmetals and nonmetals form covalent compounds
I got that pH=3.65 using the fact that Ka=[H⁺][A⁻]/[HA] at equilibrium. In the ice table, I stands for initial, C stands for change, and E stands for equilibrium.
I hope this helps. Let me know if anything is unclear.
(7.3 x 10^29 atoms) / (24 atoms/molecule) / (6.022 x 10^23 molecules/mol) =
5.1 x 10^4 mol C6H12O6