Via half-life equation we have:

Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes. By plugging those values in we get:

There is 6.25 grams left of Ra-229 after 12 minutes.
<span>A change in the pressure of a gas results in a more significant change in volume than it would in a liquid. is the statement that accurately describes the property of gas. Gas only depends on how you store it. the bigger the space the wider gas can expand, the smaller the space, the more compress the gas can become.</span>
I think the answer would be : A. more powerful
The shorter the electromagnetic wave is, the closer it is to the electromagnetic core, which make it more powerful
hope this helps