Answer:
Physical change
Explanation:
It is a physical change because a physical change involves alteration in physical properties or appearance in color, sizes e.t.c but no new substances is formed. From the question, CoCl2 undergo a physical change because it's physical property which is color changed , its composition is not altered or no new substances is formed during the reaction.
Krypton is group 8 (or 18 depending on your choice of convention) and period 4.
Not sure what you mean by region, it's not a chemistry term in the context you're presenting. If you're asking for what type of element it is, it's a noble gas.
First of all there nothing exists something like SSA congruence criterion, It is SAS Congruence where the sides of a Triangle and the angle between them is exactly same to the other two sides and angle between them of another triangle.
So the correct option is D.
Explanation:
If the Triangle has two sides equal, so the two angles there are equal. Also the other angle be some other definite angle. So
45+x+x=180(Considering definite angle to be 45)
2x=135
x=67.5
So there is only one solution to the triangle.