Put the following stages of star formation into the proper sequence from earliest to latest:

Hint: When put into the proper order, each stage connects to the one before it and the one after it. Look for the key transition terms.

A. Infalling material forms a hot and luminous protostar at the center of the disk.

B. Newly-formed star settles onto the Main Sequence.

C. Massive, rotating, amorphous interstellar cloud collapses and fragments.

D. As the shrinking protostar heats up, hydrogen is ionized and a magnetic field forms.

E. Gravitational contraction causes protostar to shrink and heat as it descends the Hyashi track.

F. Magnetic bipolar outflows begin along rotation axis as the magnetic field forms.

G. Shrinking cloud collapses into a flat disk shape.

H. As bipolar outflows become stronger, powerful T-Tauri winds start clearing the nebula before the onset of nuclear fusion.

I. Onset of nuclear fusion in the core occurs around 15 million K.

C → A → E → D → F → H → G → I → B

Explanation:

Put into the proper order, the following are the stages of star formation  from earliest to latest:

Massive, rotating, amorphous interstellar cloud collapses and fragments → Infalling material forms a hot and luminous protostar at the center of the disk → Gravitational contraction causes protostar to shrink and heat as it descends the Hyashi track → As the shrinking protostar heats up, hydrogen is ionized and a magnetic field forms → Magnetic bipolar outflows begin along rotation axis as the magnetic field forms → As bipolar outflows become stronger, powerful T-Tauri winds start clearing the nebula before the onset of nuclear fusion → Shrinking cloud collapses into a flat disk shape → Onset of nuclear fusion in the core occurs around 15 million K → Newly-formed star settles onto the Main Sequence

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.