Hello.
When dealing with two or more elements in a fixed proportion, your answer is going to be "B.) Compound." The explanation is pretty basic when you narrow it down - think of it like the English version of a compound sentence; there are two independent clauses that have related ideas (such as this one, for example).
Let's use an example of a compound element, such as

, or Water.
This is a compound element that is composed of the two elements "Hydrogen" and "Oxygen" - for every 2 Hydrogen atoms there is one Oxygen atom.
I hope this helps!
<u>Given</u>:
Wavelength (λ) of the laser pulse = 545 nm = 5.45 * 10⁻⁹ m
Total energy of pulse = 4.85 mJ
<u>To determine:</u>
The number of photons in the laser of a given energy
<u>Explanation:</u>
Energy per photon (E) = hc/λ
where h = planck's constant = 6.626 *10⁻³⁴ Js
C = speed of light = 3*10⁸ m/s
λ = wavelength
E = 6.626 *10⁻³⁴ Js* 3*10⁸ms-1 /5.45 * 10⁻⁹ m = 3.65 * 10⁻¹⁹ J
Now,
# photons = total energy/Energy per photon
= 4.85 * 10⁻³ J* 1 photon / 3.65 * 10⁻¹⁹ J = 1.32 * 10¹⁶ photons
Ans: the laser pulse contains 1.32 * 10¹⁶ photons
Answer:
rA = 0.60 M/s
rC = 0.90 M/s
Explanation:
Let's consider the following reaction:
2 A+B ⇒ 3 C
The rate of each substance can be calculated like the change in its concentration divided by the change in time. Given the rate must always be positive, we add a minus sign before the reactants change in concentration.
![rA=-\frac{\Delta[A] }{\Delta t}](https://tex.z-dn.net/?f=rA%3D-%5Cfrac%7B%5CDelta%5BA%5D%20%7D%7B%5CDelta%20t%7D)
![rB=-\frac{\Delta[B] }{\Delta t}](https://tex.z-dn.net/?f=rB%3D-%5Cfrac%7B%5CDelta%5BB%5D%20%7D%7B%5CDelta%20t%7D)
![rC=\frac{\Delta[C] }{\Delta t}](https://tex.z-dn.net/?f=rC%3D%5Cfrac%7B%5CDelta%5BC%5D%20%7D%7B%5CDelta%20t%7D)
The rate of the reaction is equal to the rate of each substance divided by its stoichiometric coefficient.

The rate of disappearance of B is 0.30 M/s.
The rate of disappearance of A is:

The rate of appearance of C is:

B add the atomic number to the number of neutrons
Yes it is incrediably harmfull