a solution with PH4 has a bases sdded to it until the PH7 by

a solution with PH=4 has a bases sdded to it until the PH=7. by what factor did the hydrogen ion concentrarion[H+] change?
A) 1/3
B) 3
c)1/100
d)1/1000
E)1000

Solution

pH is the negative logarithm of hydrogen ion concentration. It is calculates as,

pH= -log [H⁺]

So, [H⁺] = 10^-pH

In this question, initially the pH is 4 and after addition of bases it becomes 7.

i. [H⁺] = 10^-4

ii. [H⁺] = 10^-7

So, to calculate by what factor, the hydrogen ion concentration change, we have to divide the  [H⁺] at pH 7 with  [H⁺] at pH 4.

= 10^-7 / 10^-4

⁼ 1/1000 times.

So, the correct answer is option D.