<span>(3) electromagnetic energy and internal energy</span>
Answer: Option (a) is the correct answer.
Explanation:
A formula that represents how atoms are linked or joined together is known as a structural formula.
For example, the model given in the image (in question) represents arrangement of all the atoms. Therefore, it is a structural formula.
Whereas a chemical formula represents a compound along with ratio of compounds.
A space filling model and a ball-stick model is a three dimensional model. In space filling model atoms are represented by spheres whereas in ball stick model atoms are represented by ball and bonds are represented by stick.
Answer:
a)
& 
b) 
c) 
Explanation:
Given:
mass of the book, 
combined mass of the student and the skateboard, 
initial velocity of the book, 
angle of projection of the book from the horizontal, 
a)
velocity of the student before throwing the book:
Since the student is initially at rest and no net force acts on the student so it remains in rest according to the Newton's first law of motion.

where:
initial velocity of the student
velocity of the student after throwing the book:
Since the student applies a force on the book while throwing it and the student standing on the skate will an elastic collision like situation on throwing the book.

where:
final velcotiy of the student after throwing the book
b)



c)
Since there is no movement of the student in the vertical direction, so the total momentum transfer to the earth will be equal to the momentum of the book in vertical direction.


