Medeleleev arranged the known chemical elements in a table according to

a) atomic number
b) number of electrons
c) number of protons
d) mass

A- atomic number.  Atomic number represents how many protons are in the element, and they are arranged this way in the table in ascending order.  

edit- on second thought they weren't technically known as atomic numbers until after he arranged them, so I guess the better answer in this case is d- mass.  It's a trick question since today they're considered arranged by atomic number

The correct answer would be b) volume versus temperature, because they are also directly proportional.

  the volume of  0.220 m k2s    solution  required  to  completely  react with 175 ml  of 0.115m co(no3)2  calculate the moles  of co(no3)2 =  molarity x volume/1000175 x0.115/1000= 0.02  moleswrite  the reacting  equationk2s(aq)  +  co(no3)2  = 2 kno3(aq)  + cos(s)by  use  of mole ratio between k2s to co(no3)2 which  is  1: 1 the moles of k2s is therefore = 175  x0.115/1000= 0.02  molesvolume = moles/molarity=0.02/0.22=0.09  ml  of k2s