The availability of calcium is highest in which of the following condition?
A. The cation exchange capacity is 24 cmol(+)/Kg, while the exchangeable calcium is 12 cmol(+)/Kg
B. The cation exchange capacity is 30 cmol(+)/Kg, while the exchangeable calcium is 8 cmol(+)/Kg
C. The cation exchange capacity is 8 cmol(+)/Kg, while the exchangeable calcium is 5 cmol(+)/Kg
D. The cation exchange capacity is 15 cmol(+)/Kg, while the exchangeable calcium is 6 cmol(+)/Kg
查看答案
The four most abundant elements in soil are ( ).
A. O, Si, Al, Fe
B. K, Na, Ca, Mg
C. O, Al, K, Na
D. Si, Al, Ca, Mg
When the pH of kaolinite suspension is increased, the absolute number of variable charges ( ).
A. increases
B. decreases
C. does not change
D. It is impossible to judge
Which of the following item has the largest specific surface area assuming that they have the same density?
A sphere with the diameter of 5 μm
B. A rectangular block with the length of 10 μm, width of 8 μm and thickness of 5 μm
C. A cube with the length of the side of 8 μm
D. A sphere with the diameter of 8 μm
Which of the following is acid cation?
A. Ca2+
B. H+
C. Mg2+
D. K+
微信支付 
支付宝支付