Which of the following best describes a mixture?

(A) a substance that can be changed into another substance

(B) a substance that has been broken down into its smallest parts

(C) a material that is made up of many molecules

(D) a material that contains two or more different substances

I keep getting ALMOST the right answer, but it doesn't seem to be asig fig issue.

Here's the question: Calculate the pH of 0.105 M CCl3COOH(pKa=0.52).

The text says the answer is 1.08. I keep getting 1.05. I don'tthink it's a rounding issue.

This might not be a good question to ask on here but I don't knowwhere else to try and get some help. What I cant figure out is whatbuttons to push on my calculater to get the right answer. I have aTI-36X Pro calculater. If anyone has any idea how I use it for thisproblem I would very much apreciate your help.

Determine the pH of an aqueous solution of CaCO3 that contains1.7*10^-6 M of hydroxide ion [OH^-].

(I need to get an answer of 8.2. This is the answer my teachergives. Others have helped me on here but gave me differentanswers.)