Misc: How much did the hammer weigh that john henry swung?

Questions

[science and technology] what is the name of the minute organisms found drifting near the surface of seas and lakes?

[science and technology] what is the name of the instrument used for measuring humidity in the air?

[science and technology] what fruit is considered to be the most nutritious?

[science and technology] the deficiency of which vitamin causes scurvy?

[science and technology] how many coloured squares has a rubiks cube?