Let us calculate the structure of the electric shells of the Al atom. It has an atomic number of 13, so it has 13 electrons. The first 2 go to the first hell. The next 8 need to go to the second shell and the last 3 ones would go to the outermost shell. The outer shell, that is the most important one for chemical reactions, has thus 3 electrons. An atom always tries to have a completed outer shell (with either 2 or 8 atoms). It is easier for a cell to have a charge of +3 than a charge of -5 (smaller absolute value) and thus the Aluminum atom will try to get rid of the 3 electrons. In this process, it loses negative charge thus it will become positively charged. Hence, the correct answer is that it will prefer to lose 3 electrons and become positively charged.
        
             
        
        
        
Mass of Co(NO₃)₂ = 1.95 g
V KOH = 0.350 L
[KOH] = 0.220 M
Kf = 5.0 x 10⁹
molar mass of Co(NO₃)₂ = 182.943 g/mol
so [Co(NO₃)₂] = 1.95 / (0.350 * 182.943) = 0.03045 M
[Co²⁺] = 0.03045 M
[OH⁻] = 0.22 M
chemical reaction:
             Co²⁺(aq) + 4 OH⁻    ⇄      Co(OH)₄²⁻
I (M)      0.03045      0.22                   0
C (M)   - 0.03045   - 4 (0.03045)      0.03045
E (M)       - x         0.22 - 4(0.03045)   0.03045
                              = 0.0982
Kf  = [Co(OH)₄²⁻] / [Co⁺²][OH⁻]⁴
5.0 x 10⁹ = (0.03045) / x (0.0982)⁴
x = 6.5489 x 10⁻⁸
at equilibrium:
[Co²⁺] = 6.54 x 10⁻⁸
[OH⁻] = 0.0982 M
[Co(OH)₄²⁻] = 0.03045 M
        
             
        
        
        
Each isotope of Oxygen has a different number of neutrons
<h3>Further explanation
</h3>
The elements in nature have several types of isotopes
Atomic mass is the average atomic mass of all its isotopes
Isotopes are atoms has the same number of protons but has a different number of neutrons.
So Isotopes are elements that have the same Atomic Number (Proton)
Some of the isotopes of oxygen are:

Each isotope has 8 protons and 8 electrons but has a different number of neutrons
For O-16: number of neutrons = 16-8 = 8
For O-17: number of neutrons = 17-8 = 9
For O-18: number of neutrons = 18-8 = 10
 
        
             
        
        
        
Answer:
Explanation:
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
Explanation:
This law was given by french chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
Chemical equation:
Mg + HCl → H₂ + MgCl₂
24 g + 36.5 g = 2 g+ 95 g
60.5 g = 97 g
The reaction does not hold the law of conservation of mass, because it is not balanced.
Balanced chemical equation:
Mg + 2HCl → H₂ + MgCl₂
24 g + 73 g = 2 g+ 95 g
97 g = 97 g
this equation completely follow the law of conservation of mass.