<span>It is amorphous because it gets softer and softer, and it doesn't melt at a distinct temperature.
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Answer:
The molar concentration of Cu²⁺ in the initial solution is 6.964x10⁻⁴ M.
Explanation:
The first step to solving this problem is calculating the number of moles of Cu(NO₃)₂ added to the solution:

n = 1.375x10⁻⁵ mol
The second step is relating the number of moles to the signal. We know the the n calculated before is equivalent to a signal increase of 19.9 units (45.1-25.2):
1.375x10⁻⁵ mol _________ 19.9 units
x _________ 25.2 units
x = 1.741x10⁻⁵mol
Finally, we can calculate the Cu²⁺ concentration :
C = 1.741x10⁻⁵mol / 0.025 L
C = 6.964x10⁻⁴ M
The volume of HCl required is 23.89 mL
Calculation of volume:
The reaction:

As HCl and NaOH react in 1 : 1 ratio.
Volume of NaOH= 718 mL
Concentration= 0.183M
Volume of HCl= ?
Concentration= 5.50M
Using the dilution formula:


Therefore,
Volume of HCl required will be 23.89 mL.
Learn more about neutralization reaction here,
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Answer:atomic mass, neutrons in the nucleus
Explanation: because I remember from when I took honors chemistry last year we learned about this and it’s called the atomic mass when looking at an atom and the neutrons in the nucleus are effected by it.
The fourth period contains 18 elements, beginning with potassium and ending with krypton. As a rule, period 4 elements fill their 4s shells first, then their 3d and 4p shells, in that order; however, there are exceptions, such as chromium.
Cr. I think