A scientist studied two species of barnacles on the shore of a scottish island. barnacles feed on plankton and dead plants and animal matter floating in the water. he found that the population of species a was smaller than that of species b. he removed species b from one area but left both species a and b in a similar area. the graph below shows the results of this study. he noticed that the population of species b decreased rapidly when it shared a location with species b. the evidence best supports which following claims? Barnacles grow larger when they are isolated from other species

there is a mutualistic relationship between the two species

the two barnacles have predator prey relationship.

the two species of barnacles complete with each other for resources.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.