Answer:
To Put of a Fire.
Explanation:
incase an emergency happens, it's important to have a fir extingushier so the situation doesn't get worse and you can put out any possible fire's.
According to ideal gas equation, we know for 1 mole of gas: PV=RT
where P = pressure, T = temperature, R = gas constant, V= volume
If '1' and '2' indicates initial and final experimental conditions, we have

Given that: V1 = 100.0 kPa, T1 = 100.0 K, V1 = 2.0 m3, T2 = 400 K, P2 = 200.0 kPa
∴ on rearranging above eq., we get V2 =

∴ V2 = 4 m3
The green and black symbols refer to atoms, that make up the molecule of water, more specifically you can say that the 2 Hydrogen atoms are the black ones found outside, while the central atom, that is also green would be oxygen.
The creator of the Polio Vaccine was Jonas Salk.
An example of an internal chemical transmitter is a hormone.