Please help me figure out these synthesis questions. Thanks

Which type of orbits are found in the principal energy level n = 2 a - s b - s, f c - s, d d - s, p e - s, p, d

In a ni-cd battery, a fully charged cell is composed of nickelic hydroxide. nickel is an element that has multiple oxidation states. assume the following proportions of the states: nickel charge proportions found 0 0.17 +2 0.3 +3 0.33 +4 0.5 (a) determine the mean of the nickel charge. enter the answer to 2 decimal places.(b) determine the cumulative distribution function of nickel charge.

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?