What is the half-life of an isotope if 62.5 g of a 500. g sample remains after 18 years? ASAP

8) a mixture of he, ne and ar has a pressure of 7.85 atm. if the ne has a mole fraction of 0.47 and 8) ar has a mole fraction of 0.23, what is the pressure of he? a) 4.2 atm b) 3.7 atm c) 5.5 atm d) 2.4 atm e) 1.8 atm

Amap that uses a range of colors and shading to represent the elevation, depth, or landscape of specific features on earth is a/an map.

Describe at least two advantages and two disadvantages of using hydropower as a source of energy.