A 202.7 ng sample of an unknown radioactive substance was placed in storage and its mass measured periodically. After 47 days the amount of radioactive substance had decreased to 25.34 ng. How many half‑lives of the unknown radioactive substance have occurred?

Ihat will happen if i added baking soda to vinegar

Diffraction is when light is bent around obstructions. which of the these observation about clouds would indicate diffraction? a) after rain storms, you can sometimes see rainbows. b) clouds are white or gray and cannot be seen through. c) on a cloudy day, the temperature tends to be cooler than a sunny day. d) the edges of dark clouds appear lighter. this

Convert the temperature of dry ice, –77 ∞c, into degrees fahrenheit and kelvin.