The answer is 5.4! I found it on a an online calculator!
21.69mL - 20.70mL = .99mL Fe
7.8 g / .99 mL = 7.9g/mL
6 sodium and 6 Bromine in 6NaBr
1. its temperature will rise continuously until it melts
I don't believe that any of the other answers are correct because it can not stay at a certain temperature if it is melting
Explanation:
It is given that,
The time period of artificial satellite in a circular orbit of radius R is T. The relation between the time period and the radius is given by :

The radius of the orbit in which time period is 8T is R'. So, the relation is given by :



So, the radius of the orbit in which time period is 8T is 4R. Hence, this is the required solution.