C. As we know, an atom is made of three parts--protons (+), neutrons (core), and electrons (-) When one of these atoms loses one or more electron(s), it becomes a cation, or a positively charged ion. Inversely, when this atom gains a positively charged ion, [the atom] becomes a negatively charged atom, or an anion. The bond is made through electrostatic attraction, and a bond between these two "halves of a whole", it is known as an ionic bond.
Answer:
* 
* The solution is acidic since the pH is below 7.
Explanation:
Hello,
In this case, we can mathematically define the pH by:
![pH=-log([H_3O^+])](https://tex.z-dn.net/?f=pH%3D-log%28%5BH_3O%5E%2B%5D%29)
Thus, for the given hydronium concentration we simply compute the pH:

Thereby, we conclude the solution is acidic due to the fact that the pH is below 7 which is the neutral point and above it the solutions are basic.
Regards.
So the first one is yellow and the other one is white
Answer:
The significance of "Er" in the diagram is :
B.) Threshold energy for reaction
Explanation:
Threshold energy : It is total amount of energy required by the reactant molecule to reach the transition state .
Activation energy : It is the excess energy absorbed by the molecules to reach the transition state.
<u>Activation Energy = Threshold Energy - Average Kinetic Energy</u>
<u>This means Activation energy decreases on increasing kinetic energy</u>
On increasing Temperature average kinetic energy of the molecule increases which reduces the activation energy and the reaction occur faster in that case.
Catalyst also reduces the Activation energy.
<u>Er = Threshshold energy for reaction at 30 degree</u>
<u>Ea = Activation Energy</u>
<u>The given figure shows that the threshold energy decreases on increasing the temperature</u>
<u>Only the molecule having energy greater than Er can react to form product</u>