I think the answer would be K.
The SI base units for length is meter (m) and for time is seconds (s).
The given ratio is 

Converting mm/s to m/s as:
Since, 1 mm/s = 0.001 m/s
So, 
Since, zeroes to the left side of the non-zero number are not significant hence, the evaluation of
to three significant figures and answer in SI units is
.
45 m. If each student needs 750 mm of tubing, the teacher should order 45 m of tubing.
a) Find the <em>length in millimetres</em>
Length = 60 students x (750 mm tubing/1 student) = 45 000 mm tubing
b) Convert <em>millimetres to metres
</em>
Length = 45 000 mm tubing x (1 m tubing/1000 mm tubing) = 45 m tubing
Answer:
+ 3
Ex planation:
Al3+ indicates an ion of aluminum having a charge of + 3. I.e., since an aluminum atom normally has 13 protons and 13 electrons, this ion has 10 electrons (-10 charge) and 13 protons (+ 13 charge) giving it a charge of + 3 (-10 + 13 = +3).
hope this helps!