Initially, a particular sample has a total mass of 200 grams and contains 128 x 1010 radioactive nuclei. these radioactive nuclei have a half life of 1 hour. (a) after 3 hours, how many of these radioactive nuclei remain in the sample (that is, how many have not yet experienced a radioactive decay)

Explanation:

Formula to calculate how many particles are left is as follows.

              N =

where,     = number of initial particles

                              l = number of half lives

As it is given that number of initial particles is and number of half-lives is 3.

Hence, putting the given values into the above equation as follows.

               N =

                    =

                    =

or,                    

Thus, we can conclude that particles of radioactive nuclei remain in the given sample.

In five hours we've gone through 5 half lives so the answer is:

particles

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .

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