W<span>hole viruses leave the host cell to infect other cells</span>
Answer:
"Earth-centered," or "geocentric" Ptolemy thought that all celestial objects — including the planets, Sun, Moon, and stars — orbited Earth. Earth, in the center of the universe, did not move at all.
Explanation:
Answer : The density of the block is estimated to be,
.
Explanation :
Density of the water, 
As we know that,
Buoyant force = 
where,
g = gravitational acceleration
volume of the block = v
density of the block = 
Weight of the Block = Buoyant force exerted by water




Thus, the density of the block is estimated to be,
.
This is a double replacement reaction; the ions switch twice.