The role of the crowbar is the same as that of the lever. It can be used in two ways as shown in the figures.

in the first image, the fulcrum is applied in the middle whereas, in the second image, fulcrum is not applied.

Explanation:

In the left image,

the crowbar turns about the little stone kept beneath it that the enormous stone gets lifted. The point about which a switch turns is known as the 'Fulcrum'.The power we apply is called Effort. The resistive power that is overwhelmed by the exertion is called Resistance. Resistance happens at the position where the heaviness of the enormous stone is experienced.

In the right image,

the force is applied directly to the enormous stone by a crowbar.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

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.