STRUCTURE S1:
Discuss how isolated gold colloidal nanoparticles in a solution can be collected based on the
DLVO theory . (10marks)

Earth is not flat because the spheroidical shape provides a more effective shape in terms of exposed surface area for absorbing and radiating radiation, and also for a relatively more uniform gravity pull on different points on its surface which might not be so for a flat surface.

You live in your country, not mine because you have evolved over time to be more adapted to living in your own kind of envoirment. Members of a certain species (like you and me as humans) have been spread to maximize the survivability of their species compared to if they were clustered to a particular place.

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.