B. A solar cycle usually lasts 11 years.
Answer:
either first or second if not them try d but I'm pretty sure a also I'm sorry if I getbyou this wrong I dearly apologize
C₀=2 mol/l
c₁=0.400 mol/l
v₁=100.0 ml = 0.1 l
c₁v₁=c₀v₀
v₀=c₁v₁/c₀
v(H₂O)=v₁-v₀
v₀=0.1*0.400/2=0.02 l = 20 ml
v(H₂O)=100 - 20 = 80 ml
It is necessary to mix 20 ml of the feed solution and 80 ml of water.
