The electron and proton numbers.
Answer: pH = 10
Explanation: First solve for pOH using the equation pOH=-log[OH-] = 4
Then plug the pOH in the equation, pH + pOH =14
then solve for pH. pH =14 - 4 = 10
Answer: It is true about the type of reaction that it is a single replacement reaction, and the cations in the two ionic compounds are different.
Explanation:
When one element in a compound is replaced by another element in a chemical reaction then it is called a single replacement reaction.
For example, 
Here, potassium metal is replacing the sodium metal in the sodium chloride compound.
As metals become cation by losing an electron in a chemical reaction.
Thus, we can conclude that it is true about the type of reaction that it is a single replacement reaction, and the cations in the two ionic compounds are different.
Answer:
Potassium (K) and Fluorine (F)
Explanation:
A salt is formed with a metal and non-metal element from the periodic table of elements. if you look at the online ptable.com the upper right hand corner of each element shows the valence electrons for each element, and how many are in each shell for that element. Fluorine (F) has 7 valence electrons in its outer most shell, which means there is room for 1 more electron since the second shell can hold a max of 8. Potassium(K) has 1 electron in its outer most shell- which means is can fill in the 1 space available that fluorine has in its outer most shell. Since Potassium(K) is a metal and Fluorine(F) is a non-metal they can form an ionic compound, salt.