Answer:
Explanation:
1. Virus's are hard to detect because of their simple construction.
2. Some mutate very easily.
3. It is hard to isolate the virus and kill it without doing damage to the host.
Answer:Zirconium is a chemical element with the symbol Zr and atomic number 40. The name zirconium is taken from the name of the mineral zircon, the most important source of zirconium. It is a lustrous, grey-white, strong transition metal that closely resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, altho…
You should never heat chemicals in a closed system (closed bottle or flask) because it might explode.
Let's consider water.
Regardless of what form it turns into, the mass should remain the same.
It's the same H20.
Add some heat and it becomes water vapor,
cool it down a bit and it becomes ice.
if you make it just right, it becomes water again.
A chemical change would involve the one or more element(s) changing into a different solution all together.
It cannot be reversed unless you use electrolysis or some other method.