15. D is correct, exothermic reactions release heat
I am not sure about 16
C. Accelerating should be the correct onw
Answer:
Germanium and Polonium
Explanation:
Can you please mark me brainliest since I was the first person to answer :p
I believe dimensional analysis
Electronic configuration of cromium is
Cr-[Ar]4s¹3d⁵
When cromium loses two electrons it becomes Cr⁺².
So its electronic configuration becomes,
Cr⁺²-[Ar]3d⁴
One electron will go from 4s orbital and one electron will go from 3d orbital.
So the answer here is D. [Ar]3d⁴ -because after losing 2 electrons electronic configuration of cromium becomes [Ar] 3d⁴.