Answer:
The electronic configuration of the element with Atomic number 19 is 2,8,8,1. The element is potassium. It is an alkali metal with one valence electron.
Answer:
A solution was NOT formed.
Explanation:
For a solution to be formed, the green powder would need to dissolve in the water to form a homogenous mixture. But since the water was cloudy and had lumps of the green powder, it means that the powder did not dissolve, but instead remained insoluble.
Answer: 
Explanation:
Electron gain enthalpy is defined as energy released on addition of electron to an isolated gaseous atom.
The amount of energy released will be maximum when the tendency to attract electrons is maximum. As flourine has atomic number of 9 and has electronic configuration of 2,7. It can readily gain 1 electron to attain stable noble gas configuration and hence liberates maximum energy.
I think the answer would be Ga3+
Answer and explanation:
A chemical change occurs when new substances or materials are produced to have different chemical properties from the reactants.
Some examples of this are paper burning, fruit rotting, and metal rusting.
