Out of the options, the best indicator is a color change since it is the only one that can't really be blamed on a physical change. you will eventually notice that during qualitative labs and some quantitative labs, usually the thing that you are looking for is either color change or the production of a precipitate to indicate the presence of a chemical reaction
Answer:
Explanation:
Chlorine has electronic configuration of 2 , 8 , 7
In n = 3 there are 7 electrons out of which 2 are in s , and 5 are in p . But out of 5 electrons in p , one electron jumps into d orbital . so the electronic configuration becomes as follows
= 7

These orbitals like sp³d hybridise to form 7 degenerate orbitals out of which 2 orbitals contain electrons in pairs and rest three are singly occupied by electrons.( unpaired electrons )