What gases are no longer traceable about 19 km up why?

7500 feet is equivalent to what miles? How many pavers 300mmx300mm do you need for an area 2.44m x 2.38m? How many times bigger than 15 is 60? How many times is the word patience used in the Bible? How to change 90 percent to a fraction? How many sections will you get if you fold a piece in half 8 times? Is 720 degrees the angle sum of a hexagon? What are the four types of 3D shapes? What utterly ridiculous or what a utterly ridiculous? How are the area of the base and the volume of that solid related? Is 44 divisible by 3? What is 140cm converted in to feet and inches? How many times is 'afraid' in the bible? What is the least number with 5 ones using 4 2 7 5? What is the cubic yards for 2 foot by 1 foot cylinder? What can a person do 10000 times a day? How many questions are on the math regents? What is the formulae for mean deviation? What is 254.34 rounded to the nearest hundredths? What is the opposite of the lowest common multiple?