Answer: The solution to the problem expressed to he correct number of significant figures is 1.69
Explanation:
Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
The rule applied for multiplication and division is :
The least precise number determines the number of significant figures in the answer.
As 12.0 has 3 significant digits and 7.11 also has 3 significant digits, the answer would also contain 3 significant digits.
For 
Thus the solution to the problem expressed to he correct number of significant figures is 1.69
The mass number of the atom is 21, the atomic number is 9, and the element is Fluorine. There are 9 protons, 9 electrons, 12 neutrons, and the elemental symbol is F.
<h3>Properties of an atom</h3>
For every atom:
- Protons and neutrons are located in the nucleus and the addition of both equals the mass number of atoms.
- Electrons are located outside the nucleus, in orbitals.
- Neutral atoms have the same number of electrons and protons
In the diagram:
Number of electrons = 9
Number of protons = 9
Number of neutrons = 12
Mass number = 12 + 9
= 21
Atomic number = number of protons
= 9
Element with atomic number 9 = Fluorine
Symbol of the element = F
More on atoms can be found here: brainly.com/question/1566330
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Answer:
C
Explanation:
Because 2 x n square gives the total energy level been absorbed = 2 x16
=32
Physical properties of matter
<u>Answer:</u> The pH of resulting solution is 8.7
<u>Explanation:</u>
To calculate the number of moles for given molarity, we use the equation:
Molarity of TRIS acid solution = 0.1 M
Volume of solution = 50 mL
Putting values in above equation, we get:
Molarity of TRIS base solution = 0.2 M
Volume of solution = 60 mL
Putting values in above equation, we get:
Volume of solution = 50 + 60 = 110 mL = 0.11 L (Conversion factor: 1 L = 1000 mL)
- To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:
![pH=pK_a+\log(\frac{[salt]}{[acid]})](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%28%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D%29)
![pH=pK_a+\log(\frac{[\text{TRIS base}]}{[\text{TRIS acid}]})](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%28%5Cfrac%7B%5B%5Ctext%7BTRIS%20base%7D%5D%7D%7B%5B%5Ctext%7BTRIS%20acid%7D%5D%7D%29)
We are given:
= negative logarithm of acid dissociation constant of TRIS acid = 8.3
![[\text{TRIS acid}]=\frac{0.005}{0.11}](https://tex.z-dn.net/?f=%5B%5Ctext%7BTRIS%20acid%7D%5D%3D%5Cfrac%7B0.005%7D%7B0.11%7D)
![[\text{TRIS base}]=\frac{0.012}{0.11}](https://tex.z-dn.net/?f=%5B%5Ctext%7BTRIS%20base%7D%5D%3D%5Cfrac%7B0.012%7D%7B0.11%7D)
pH = ?
Putting values in above equation, we get:
Hence, the pH of resulting solution is 8.7
