Answer:
The Laura tried to grow micro-organisms in culture broth medium in Petri-plates but the microbial growth was not observed even on the fourth day of culture which could be due to:
1. Laura could have not provided the correct broth medium maintaining the with pH and salt concentrations.
2. Microorganisms did not get optimal growth conditions.
3. The bacterial source could have died after the collection which could have lysed after their death and thus no longer visible.
Recall that a period is horizontal, and a group is vertical.
So if cobalt is moving "down" a period, it would be most logical to say that it would be Ni, or nickel. It could also be Copper, Zinc, Gallium, and so on. Make sense?
Mechanical energy turns into kinetic
Жила была царевна но туда ей бросил лёд
