If the contents of exchangeable ions (cmol kg-1) determined in soil are Na+ = 5, K+ = 5, Ca2+ = 10, Mg2+ = 2, H+ = 1, Al+3 = 1, Cl- = 1.6 and HCO-3 =0.4, the CEC of soil is

Answer: Option C

CEC is cation exchange capacity is a measure of the soil’s ability to hold positively charged ions.
If the contents of exchangeable ions (cmol kg^-1) determined in soil are
Na⁺ = 5
K⁺ = 5
Ca²⁺ = 10
Mg²⁺ = 2
H⁺ = 1
Al⁺³ = 1
Cl^- = 1.6
HCO^-₃ = 0.4
Summing up all the values of positive ions, we get the value of CEC of soil i.e. 24 cmol (P⁺) kg^-1