<h3>
Answer:</h3>
4.227 × 10^-19 Joules
<h3>
Explanation:</h3>
Energy of a photon of light is calculated by the formula;
E = hf, where h is the plank's constant, 6.626 × 10^-34 J-s and f is the frequency.
But, f = c/λ
Where, c is the speed of light (2.998 × 10⁸ m/s), and λ is the wavelength.
Given the wavelength is 470 nm or 4.7 × 10^-7 m
Therefore;
E = hc/λ
= (6.626 × 10^-34 J-s × 2.998 × 10^8 m/s) ÷ 4.7 × 10^-7 m
= 4.227 × 10^-19 Joules
Therefore, the energy of a photon with 470 nm is 4.227 × 10^-19 Joules
Answer:
3.63m/s²
Explanation:
Given parameters:
Mass of box = 8kg
Net force = 29N
Unknown:
Acceleration of the box = ?
Solution:
To solve this problem, we use Newton's second law of motion which is stated as;
Force = mass x acceleration
Acceleration =
=
Acceleration = 3.63m/s²
Answer: a)
and pH = 1.04
b)
and 
c)
and ![[OH^-]=1.41\times 10^{-4}](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.41%5Ctimes%2010%5E%7B-4%7D)
Explanation:
pH or pOH is the measure of acidity or alkalinity of a solution.
pH is calculated by taking negative logarithm of hydrogen ion concentration.
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)

a) ![[H^+]=0.090M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D0.090M)
![pH=-\log [0.090]=1.04](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5B0.090%5D%3D1.04)

![12.96=-log[OH^-]](https://tex.z-dn.net/?f=12.96%3D-log%5BOH%5E-%5D)
![[OH^-]=1.09\times 10^{-13}](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.09%5Ctimes%2010%5E%7B-13%7D)
b) ![[OH^-]=0.00098M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D0.00098M)
![pOH=-\log [0.00098]=3.01](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5B0.00098%5D%3D3.01)

![10.99=-log[H^+]](https://tex.z-dn.net/?f=10.99%3D-log%5BH%5E%2B%5D)
![[H^+]=1.02\times 10^{-11}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D1.02%5Ctimes%2010%5E%7B-11%7D)
c) 
![10.15=-\log [H^+]](https://tex.z-dn.net/?f=10.15%3D-%5Clog%20%5BH%5E%2B%5D)
![[H^+]=7.08\times 10^{-11}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D7.08%5Ctimes%2010%5E%7B-11%7D)

![3.85=-log[OH^-]](https://tex.z-dn.net/?f=3.85%3D-log%5BOH%5E-%5D)
![[OH^-]=1.41\times 10^{-4}](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.41%5Ctimes%2010%5E%7B-4%7D)
Number of atoms : 1.26 x 10²³
<h3>Further explanation </h3>
The mole is the number of particles(molecules, atoms, ions) contained in a substance
1 mol = 6.02.10²³ particles
Can be formulated
N=n x No
N = number of particles
n = mol
No = Avogadro's = 6.02.10²³
0.21 moles of Al, so n = 0.21
Number of atoms :

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