The correct answer to this question is A, 2. Strontium is a chemical element. It is metal, which is soft and silver. Strontium has several uses. One important use is that it blocks X-rays that TV tubes emit. Strontium is also what allows glow in the dark paint to do what its name says.
One use that all will be familiar with is related to fireworks. The color red that we sell in fireworks is Strontium. It is highly reactive and is the 15th most abundant element on Earth. Its atomic number is 38, and the symbol is Sr. When Strontium is at room temperature, it is solid.
The correct answer is option A
Strontium belongs to group two elements on the periodic table, with an atomic number of 38; it is part of the alkaline earth metals. The electronic configuration of Strontium is 2, 8, 18, 8, 2. It has 2 atoms in its 5s shell and the remaining 36 are considered internal.
This shows that it has two valence electrons. The neutral strontium has 38 protons in its nucleus and 38 electrons. The oxidation number of strontium is 0 while that of strontium ion is +2.
Hope this helps.