<span>d.rotating counterclockwise and slowing down
This is a matter of understanding the notation and conventions of angular rotations. Positive rotations are counter clockwise and negative rotations are clockwise. An easy way to remember this is the "right hand rule". Make a closed fist with your right hand and have the thumb sticking outwards. If you orient your thumb such that it's pointing in the direction of the positive value along the axis, your fingers will be curled in the positive rotational direction. So in the described scenario, the sphere is rotating in the positive direction (counter clockwise) and decelerating due to the negative angular acceleration. That immediately indicates that options "a", "b", and "e" are wrong since they mention the sphere going clockwise at the beginning. Of the two remaining options "c" and "d", we can discard option "c" since it has the rotation speeding up, and that leaves us with option "d" where the sphere is rotating counter clockwise and slowing down.</span>
Answer:
a)The approximate radius of the nucleus of this atom is 4.656 fermi.
b) The electrostatic force of repulsion between two protons on opposite sides of the diameter of the nucleus is 2.6527
Explanation:

= Constant for all nuclei
r = Radius of the nucleus
A = Number of nucleons
a) Given atomic number of an element = 25
Atomic mass or nucleon number = 52


The approximate radius of the nucleus of this atom is 4.656 fermi.
b) 
k=
= Coulombs constant
= charges kept at distance 'a' from each other
F = electrostatic force between charges


Force of repulsion between two protons on opposite sides of the diameter



The electrostatic force of repulsion between two protons on opposite sides of the diameter of the nucleus is 2.6527
If an atom gains electrons, it develops a negative charge equal to the number of electrons gained.
So the net charge on the copper atom which gained 2 electrons will be -2.
Answer:
Masa, m = 0.088 kg
Explanation:
Given the following data;
Temperatura inicial = 30°C
Temperatura final = 120°C
Capacidad calorífica específica = 138J/kg.K
Calor absorbido, Q = 4400 cal.
Para encontrar la masa;
La capacidad calorífica viene dada por la fórmula;
Dónde;
Q representa la capacidad calorífica o la cantidad de calor.
m representa la masa de un objeto.
c representa la capacidad calorífica específica del agua.
dt representa el cambio de temperatura.
dt = T2 - T1
dt = 120 - 30
dt = 90°C to kelvin = 273 + 90 = 363K
Sustituyendo en la fórmula, tenemos;
Masa, m = 0.088 kg