Explanation:
Picture A which shows an overall negative charge represents an anion. Anion are formed when an atom gains an electron. In doing that, the total number of electrons (negative charge) is greater than the number of protons (positive charge), hence it would have an overall negative charge.
Picture B which shows a neutral charge represents a neutral atom. In an atom, the number of electrons equals the number of protons.
Picture C which shows an overall positive charge represents a cation. Cation are formed when an atom loses an electron. In doing that, the total number of electrons (negative charge) is less than the number of protons (positive charge), hence it would have an overall positive charge.
The excess reactant is Aluminum.
<u>Explanation:</u>
We have to write the balanced equation as,
4 Al+ 3 O₂ → 2 Al₂O₃
According to the molar ratio 4: 3, from the given balanced equation, we can say that 4 atoms of Al reacted with 3 molecules of oxygen.
Given that 10 atoms of aluminum reacts with 6 molecules of oxygen, as per the ratio only 8 atoms of Aluminum is required to react with 6 molecules of oxygen, so excess reactant is Aluminum.
<u>Answer:</u> The volume of HBr solution required is 130.16 mL
<u>Explanation:</u>
To calculate the concentration of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is 
We are given:

Putting values in above equation, we get:

Hence, the volume of KOH solution required is 130.16 mL
Answer:
The balance of chemical equation is given below.
3Ca + N2------ Ca3N2
Carbon dioxide is through the plants