If you need to measure the mass of a greeting card you are sending to a friend through the mail, what unit of measurement would you use

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5

Asample of air with a volume of 2.20m3 at a pressure of 105 kpa and a temperature of 30c is cooled to 10c and the pressure is reduced to 75.0 kpa. what is the new volume? 6.9 1.34 2.56 43.0 2.88