I don't understand or see for the matter the question what is it
Answer:
![[H^{+} ]= 10^{-pH}](https://tex.z-dn.net/?f=%5BH%5E%7B%2B%7D%20%5D%3D%2010%5E%7B-pH%7D)
Step-by-step explanation:
To solve this question it is important to remember logarithm rules. That is:
![pH = -log[H^{+}]\\\\-pH = log_{10}[H^{+} ]\\\\H^{+}] = 10^{-pH}\\](https://tex.z-dn.net/?f=pH%20%3D%20-log%5BH%5E%7B%2B%7D%5D%5C%5C%5C%5C-pH%20%3D%20log_%7B10%7D%5BH%5E%7B%2B%7D%20%5D%5C%5C%5C%5CH%5E%7B%2B%7D%5D%20%3D%2010%5E%7B-pH%7D%5C%5C)
Four significant is an answer
because if 0 is the extreme right of decimal place it is significant
and if 0 lies between two significant figure than it is significant like 1.020 is 4 sifnificant and 100 is 1 significant figure
so you know the expression r<-0.9, so you put the point on -0.9.... then, you know that the variable "r" is on the left side of the expression (which is where you want it) so you know that the value of the variable has to be less than -0.9... so which way does the arrow go? to the left, since the numbers get smaller when you go to the left. Then, you have to figure out... open or closed circle? It will be an OPEN circle, because the expression is set to LESS THAN,rather than LESS THAN OR EQUAL TO. So you will have your dot on -0.9, an open circle (the third one at the bottom) and the arrow will be going to the left. HOPE THIS HELPED!! :)
