A. Controlled experiment hope this helps
Answer:
c.
Explanation:
From the options provided the best description of scissor is that scissors helps to scrap things down. This is the main purpose of scissors, to cut things, and by doing so you are breaking up a larger object into smaller and more manageable scraps. We can get rid of the other options because scissors are made of metal and therefore not soft and are not necessarily dull since they need to be sharp to fulfill their purpose. Although a pair of scissors has two holes it is not necessarily the best description of it.
The right answer is “Atoms “
<span>3.2 grams
The first thing to do is calculate how many half lives have expired. So take the time of 72 seconds and divide by the length of a half life which is 38 seconds. So
72 / 38 = 1.894736842
So we're over 1 half life, but not quite 2 half lives. So you'll have something less than 12/2 = 6 grams, but more than 12/4 = 3 grams.
The exact answer is done by dividing 12 by 2 raised to the power of 1.8947. So let's calculate 2^1.8947 power
= 12 g / (e ^ ln(2)*1.8947)
= 12 g / (e ^ 0.693147181 * 1.8947)
= 12 g / (e ^ 1.313305964)
= 12 g / 3.718446464
= 3.227154167 g
So rounded to 2 significant figures gives 3.2 grams.</span>
