Answer:
Explanation:0.493 M NaOH means 0.493 mol NaOH/L
mols
mols = ------ x L
L
mols = M x V
In a titration procedure, 40.57 mL of 0.493 M NaOH solution was used. How many mols NaOH did this volume of NaOH solution contain?
mols = M x V
0.493 mols NaOH
mols = ----------------------- x 0.04057 L
L
mols = 0.0200 mols NaOH
Well, torr and Hg are different units, but they have the same conversiton with atm.
The conversion for atm to torr or mmHg is 1 atm = 760 torr = 760 mmHg.
Because you have 6.75 atm you can find both the torr and mmHg.
To use dimensional analysis just make sure that you cancel out your units as you go.
6.75 atm * (760 torr / 1 atm) = 5130 torr or 5.13 x 10 to the -3 torr with significant figures.
I hope this helped.
The symbol : 
<h3>Further explanation
</h3>
There are two components that accompany an element, the mass number and atomic number
Atoms are composed of 3 types of basic particles (subatomic particles): <em>protons, electrons, and neutrons
</em>
The Atomic Number (Z) indicates the number of protons and electrons in an atom of an element.
Atomic number = number of protons = number of electrons ⇒ neutral number
Atomic mass is the sum of protons and neutrons
Atomic Number (Z) = Atomic mass (A) - Number of Neutrons
The element has 71 electrons and a charge of +1 , so
Number of protons = 71 + 1 = 72
Number of protons = the atomic number = 72
The element with atomic number 72 is Hafnium(Hf)
The atomic mass of Hf = 178 g/mol
The nucleus while large has a small ratio of mass when dealing with atoms, they are very spread out and are mostly solid with a blocky shape.
The answer would be 1,3,1,3