Bebé, no lo sé, ¡pero buena suerte con la escuela! P
Protons are not the only subatomic particle that has a charge, electrons do to and they are negatively charged. Neutrons are situated in the nucleus of the atom, which means that they do not orbit it. Subatomic particles have different masses.
You are then left with Electrons are the subatomic particles with the smallest mass as your answer.
Answer:
[α] = -77.5° / 
Explanation:
Given;
Mass of optically pure substance in the solution = 10 g
Volume of water = 500 mL
Length of the polarimeter, l = 20 cm = 20 × 0.1 dm = 2 dm
measured rotation = - 3.10°
Now,
The specific rotation ( [α] ) is given as:
[α] = 
here,
α is the measured rotation = -3.10°
c is the concentration
or
c = 
or
c = 
or
c = 0.02 g/mL
on substituting the values, we get
[α] = 
or
[α] = -77.5° / 
Hope this helps! If you dont understand balancing equations in general, say so in the comments, I’m happy to help