Using the equations
H2 (g) + F2 (g) → 2 HF (9) AH° = -79.2 kJ/mol
C(s) + 2 F2 (g) CF, (g) AH° = 141.3 kJ/mol
Determine the enthalpy for the reaction
C(s) + 4 HF (g) - CF. (g) + 2 H2 (g).

Flourine is found to undergo 10% radioactivity decay in 366 minutes determine its halflife

Aradio signal from a gps satellite take only about 0.067 seconds to reach a gps reciever. if the speed of light is about 300,000km/s, then approximately how far away is the reciever from from the satellite?

The twister and runaway train are two coasters at the same amusement park. both coasters start at the same height. the coaster for the twister is twice the mass of the coaster for the runaway train. which roller coaster has greater gravitational potential energy at the start of the ride?