Answer : The number of marbles lined up across the circumference of the earth can be, 
marbles
Explanation :
First we have to calculate the diameter of tiny marble.
r = radius of marble = 0.25 mm
Now we have to calculate the number of marbles can be lined up across the circumference of the earth.
Given:
Circumference of the earth distance = 
conversion used: 
Number of marbles can be lined up = 
marbles
Thus, the number of marbles lined up across the circumference of the earth can be, marbles
High pressure and low temperature.
13
The parent atom,
Z
=
13
, necessarily has 13 electrons.....
Explanation:
And thus the trivalent ion has 10 electrons.....to give the tripositive charge.
The atoms become larger, the intermolecular forces between the atoms become stronger and more energy is needed to overcome these forces. Hence, the boiling point of noble gases increases down the group.
What are noble gases?
- Group 18 of the modern periodic table consists of noble gases. Helium, neon, argon, krypton, xenon, and radon are noble gases.
- These gases are monoatomic and chemically inert under normal conditions and because of this they are also called inert gases. These gases are present in very small quantities in the atmosphere, and so they are also called rare gases.
Trends in Physical Properties of Noble Gases:
- Atomic Radii (Atomic size): As we move down the group from helium to radon the atomic size of Noble Gasses keeps on increasing. This is because when going down the group, the number of occupied shells with valence electrons increases.
- Boiling and Melting Points: As we move down the group, the boiling and melting point of the Noble Gasses increases due to the following reason:When moving down in the group, the atomic radius increases which results in the formation of a strong Van Der Waals force of attraction between the atoms.As to overcome the interatomic force of attraction which becomes stronger, it also requires more energy during melting and boiling.
- Density: All elements of group 18 have low densities. When going down the group, density increases as the atomic mass keeps on increasing.
- Ionization Energy: In the periodic table, As we move down the group the first ionization energy keeps on decreasing.
- Ionization Potential: When going down the group, the atomic radii increases which increases the attractive force and ultimately results in the increase of polarity and decrease in the ionization potential. This is because the larger atom of the group in the valence electrons are held together less tightly by the atom as they are situated far away from the nucleus.
To learn more about trends in noble gases:
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Answer:
The concentration of the acid is 117.92 ± 0.03 mM.
Explanation:
In this problem, the concentration of NaOH and the volume used is given. The volume pipetted from the acid is also given. The concentration of the acid is given by:
CNaOH * VNaOH = Cacid * Vacid
158.32 * (18.76-0.14) = C acid * 25
C acid = 117.92 mM
The propagation of error for this problem, which is a multiplication is the concentration of the acid multiplied by the error divided by its respective value as shown in the equation below
error = 117.92 * 
The answer is 0.03 mM of uncertainty.
