After two half-lives or 60 years, 7.5 g of the element will be left.
<u>Explanation:</u>
<u>Half-life:</u>
- In simple words, Half-life can be defined as the amount of time needed for a quantity to fall to half its value as contained at the beginning of the time period.
- In this problem the half-life of the element is thirty years, then after thirty years half of the sample would have decayed and half would be left as it is.
- After thirty years (The first half-life ) 30 /2 = 15 g declines and 15 g remains disappeared.
- And after another sixty years (The two half-lives) 15 /2 = 7.5 g declines and 7.5 g remains disappeared.
- After two half-lives or 60 years, 7.5 g of the element will be left.
<span>A) Leg of a horse and the leg of a dog.
The rest of the choices are examples of convergent evolution because they are similar in structures that evolved in separate places in the animal kingdom.
>Bats are mammals and birds are not, yet they both evolved a similar appendage</span><span>
Choices to this question are:
A)
the leg of a horse and the leg of a dog
B)
the wing of a bat and the wing of a bird
C)
the fin of a dolphin and the fin of a shark
D)
the beak of a bird and the beak of a turtle</span>
Answer:
2 and 4
Explanation:
Those eat things to become secondary
Mohs scale is used to identify hardness if he minerals. There is no scale to identify rocks Bc rocks are rocks
