Answer: Creative thinking
Explanation:
It should be noted that, Creative Thinking is the method by which a problem is solved with the help of thinking skills.
The thought that is present in mind is tries in the practical life so that the problem can be solved.
Going by the question asked, Mandleev was trying to arrange elements in a logical way. He thought of arranging the elements based on the atomic weight.
This gives a good oexample of creative thinking in which the thinking is applied and a logical result is product of the thinking.
