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.
<h2>2) Copernicus rediscovered Aristarchus’s heliocentric model.</h2>
Before Copernican Revolution, people did believe in the ptolemain model that establishes the description of the Universe with the earth at the center having sun, moon, starts and planets all orbited earth. On the other hand, the heliocentric model establishes the sun at the center of the solar system and this starts with the publication of Nicolas Copernicus named <em>De revolutionibus orbium coelestium.</em>
<h2>5) Newton’s theories of gravity increased understanding of the movement of planets.</h2>
The revolution ended with Isaac Newton's work over a century later. As you well know, Newton was both a physicist and mathematician, better known for his prodigal work called <em>Philosophiæ Naturalis Principia Mathematica. </em>In this revolution, he is known for his laws of motion and universal gravitation increasing understanding of the movement of planets.
Because the gas has left which once you open the soda can u can see the fizzy which is gas coming out of it
Given data:
* The extension of the steel wire is 0.3 mm.
* The length of the wire is 4 m.
* The area of cross section of wire is,

* The young modulus of the steel is,

Solution:
The young modulus of the steel in terms of the force and extension is,

where F is the force acting on the steel wire,, l is the original length of the wire, dl is the extension of the wire, and A is the area,
Substituting the known values,

Thus, the force which produce the extension of 0.3 mm of the steel wire is 31.5 N.
Answer:
Carbon dioxide
Explination:
I remember it from biology.
I hope this helps ^-^