Physical. chemical only applies when it undergoes a reaction
At the end of the reaction, the catalyst is UNCHANGED.
:)
Answer:
Like most other metals, Gallium is solid at room temperature (or liquid if it is too hot in your room). But, if it is held [in hands] for long enough, it melts in your hands, and doesn't poison you like Mercury would. This is because of its unusually low melting point of (~29 degree Centigrade).
- It melts once it reaches its melting point.
:)
The accepted concentration of chlorine is 1.00 ppm that is 1 gram of chlorine per million of water.
The volume of water is
.
Since, 1 gal= 3785.41 mL
Thus, 
Density of water is 1 g/mL thus, mass of water will be
.
Since, 1 grams of chlorine →
grams of water.
1 g of water →
g of chlorine and,
of water →86.6 g of chlorine
Since, the solution is 9% chlorine by mass, the volume of solution will be:

Thus, volume of chlorine solution is 9.62\times 10^{2} mL.
The first three quantum numbers for electrons located in subshell 4s are :