How many moles of nacl must be dissolved in 0.5 l of water to make a 4 mole/l

C = 4 mol/l
v = 0.5 l

n(NaCl)=cv

n(NaCl) = 4 mol/l · 0.5 l = 2 mol

2 moles of NaCl must be dissolved

Ithink that the use of creativity in the sciences entails that one produce something out of nothing or from another thing. with this, i think that the he wrote down his results as four parts of the atomic theory is the manifestation of the  creativity of john dalton.