You answer this by using the pH formula and and the relation of pH and pOH, pH = -log[H+] and 14 = pH + pOH. The correct classification are as follows:
<span>A. [H2O+]=6.0x10^-12
basic
B. [H3O+]=1.4x10^-9
basic
C. [OH-]=5.0x10^-12
acidic
D. {OH-]=3.5x10^-10
acidic
Hope this answers the question.
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Answer: Read Explanation
Explanation: Index fossils are useful because they tell the relative ages of the rock layers in which they occur. Geologists use particular types of organisms, such as trilobites, as index fossils.
Answer: 
Explanation: A double displacement reaction is one in which exchange of ions take place.
The compounds which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Thus the exchange of ions take place and all the compounds are soluble so the chemical formulas are followed by the symbol (aq).
Answer:
They are magnetic lines and theses lines depict the invisible magnetic field around the magnet! Hope this helps I got it right on my quiz:)
Explanation: