I’m not entirely certain, but usually, spring symbolizes rebirth.
Answer:

Explanation:
P = Pressure = 
V = Volume = 1 cm³
n = Amount of substance
N = Number of atoms
= Avogadro's constant = 
R = Gas constant = 8.314 J/k mol
T = Temperature = 273.15+20 = 293.15 K
From the ideal gas law



The number of atoms is 
Honestly i don’t know but I’d just guess if I were you
Answer:
Please find detailed explanation of second class levers below
Explanation:
Levers are one of the classes of machine that possesses three levels namely: first class, second class and third claas. A second class lever is the level of levers in which the load (L) is in between the pivot (F) and the effort (E).
Examples of second class levers include; wheelbarrow, a bottle opener etc. In the bottle opener for example, the bottle lid (load) is in between the pivot of the opener and the hand opening it (effort).
A and c
Because it defines the boundaries of the system