'Density' is defined as (mass) / (volume). You need enough information to be able to measure or calculate the mass and the volume of the object.
Potassium is in the most reactive group of elements, the alkali metals, but it's not the most reactive metal within the group. The alkali metals, Group 1A, are the most reactive metals because they have one valence or outer electron. They lose this electron very easily, forming ions with a charge of +1.
<h2>
It takes 6.78 seconds to complete 12 dribbles.</h2>
Explanation:
Frequency of dribble = 1.77 Hz
That is
Number of dribbles in 1 second = 1.77

Now we need to find how long does it take for you to complete 12 dribbles.
Time taken for 12 dribbles = 12 x Time taken for 1 dribble
Time taken for 12 dribbles = 12 x 0.565
Time taken for 12 dribbles = 6.78 seconds
It takes 6.78 seconds to complete 12 dribbles.
Work package. Hope this helps!