Question

Which base is the strongest?

Answer 1

Answer:

The strong base  is with $H^+$ concentration equals to $1 \times 10^{-12} M$.

Explanation:

The pH of the solution is defined as negative logarithm of $H^+$ ions in a solution.Higher the $H^+$ ions concentration lower will be the value of pH and more acidic will be the solution.

$pH=-\log[H^+]$

1)$[H+] = 1 \times 10^{-9} M$

$pH=-\log[1 \times 10^{-9} M]=9$ Most acidic solution

2) $[H+] = 1 \times 10^{-11} M$

$pH=-\log[1 \times 10^{11} M]=11$

3) $[H+] = 1 \times 10^{-10} M$

$pH=-\log[1 \times 10^{-10} M]=10$

4)$[H+] = 1 \times 10^{-12} M$

$pH=-\log[1 \times 10^{-12} M]=12$ Most basic solution

Answer 2

Im assuming that 10-9, 10-10... is 10 to the power of 9 and 10 to the power of 10, respectively.

In the pH scale, acids are pH<7 and bases have pH>7. Each increase in pH makes something less acidic (or more basic) by 10.
Therefore [H+]=1x10^12 is the most basic