Which of these events indicate that a chemical reaction might have occurred? A. Silver jewelry becomes dark because of tarnish B. Water evaporates from salt water and leaves salt behind C. A liquid bubbles when heated D. A solid appears when two water-based solutions are added together. ​

Aphysical change is a change in the size, shape,, or stafe of matter true or false

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.

Will mark brainliest! asap! ! 16) which of the clouds shown would indicate a possible future rain storm? a) b) c) d)