Answer:
PERIODS
Explanation:
As with any grid, the periodic table has rows running left to right, and columns running up and down. The rows are called PERIODS and the columns are called GROUPS.
It is use by Eye Care Professionals To check the eyesight of a person.
If u would have visited a eye care centre u would have noticed a chart like this--
If a person can see all the letters from a distance his eyesight is Perfect.If that person misses a letter or a line from the grid eye treatment or spectacles are given to the person for improving their eyesight
Answer: Avoid spilling of chemicals
Explanation:
The chemicals should be kept in air tight containers in order so that they cannot get spill over each other.
Cross contamination takes place when a different type of substance comes in contact with the different kind of substance.
The chemicals should be kept in a way that it does not comes in contact with the different one and get spoiled.