Which ion makes the waste alkaline in sodium chloride

Why does his teacher ask him to balance the equation by including the correct coefficient

How many neutrons does an element have if its atomic number is 50 and its mass number is 166

2-bromo-2-methylbutane undergoes an e1 elimination reaction in the presence of ethanol. in the next reaction only one of the possible products is represented. although the product shown is not the major product of the reaction, notice that there is more than one way it can be produced. complete the mechanism and draw the missing substances.