we have,
wavelenght=c/f
where c= 3×10^8 m/s
f=6.3×10^12 s^-1
so wavelength=(3×10^8)/(6.3×10^12)
=0.476×10^-4 m
H2O became a vapor when heated because thats the only one that can go back to its normal state, which is what a physical change is.
Answer:
A.
Explanation:
Physical properties are characteristics of a substance that can be observed or measured without changing the composition of the substance. Some examples of physical properties are its volume and its density. There are two types of physical properties, intensive physical properties and extensive physical properties.
I think the answer is B...
I am not sure
Answer:
- The last option: <u><em>Decrease the volume to increase pressure and to increase concentration.</em></u>
Explanation:
You can support your choice on basis of the collision theory.
According to the collision theory, the chemical reactions happen when the molecules collide with each other, in the correct orientation and with enough kinetic energy to overcome the activation energy.
As consequence, the larger the number of collisions the larger the rate of a reaction.
In the case of a reaction that involves gases, decreasing the volume, will increase the pressure and the concentration (volume is inversely related to both the pressure and the concentration) causing the molecules to be closer to each other and to collide with higher frequency, this is you will expect more collisions, and so an increase on the rate of the reaction. That is expressed by the last choice: decrease the volumen to increase pressure and to increase concentration.
