Radium-221 has a half-life of 30 s. how long will it take for 95% of a sample to decay

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?

What type of radiation is lead emitting in the following equation? alpha particles beta particles gamma rays

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.