Which material typically make up the a horizon in soil

What is the ph of a solution with a 1.50 × 10−9 m hydroxide ion concentration?

An experimental procedure requires a 10 ml of acid to be dissolved

Mike and mitchell decide to have a foot race. they mark off a stretch of 100 yards, and recruit cindy to work the stopwatch. after running the race and looking at the results, cindy declared that mitchell was the fastest. so how did the boys times compare?