Answer:
Carbon atoms in graphite and diamond are arranged in different ways. Hence, the two allotropes of carbon have different physical properties.
Explanation:
Both graphite and diamond are both made of only carbon atoms. However, their physical properties differ from each other. Hence, they are called allotropes. Think about how these carbon atoms are arranged in each of the allotropes.
<h3>Graphite</h3>
In graphite, each carbon atom is bonded to three other carbon atoms. These carbon atoms will be located in the same plane. A chunk of graphite can contain many of these planes.
Each carbon atom has four valence electrons. Three of these electrons will be used in the bonds. The other electron will be delocalized. These electrons would flow between the sheets of carbon atoms. That keeps the sheets separate and allow them to slide on top of each other.
<h3>Diamond</h3>
In diamond, each carbon atom is bonded to four other carbon atoms. These carbon atoms will form a tetrahedral network.
In graphite, there's a significant separation between two adjacent sheets of carbon atoms. The force between the two sheets is rather weak. When a piece of graphite is between two objects that move over one another, the layers in the graphite would also slide over one another. Since the attraction between two adjacent sheets isn't very strong, there wouldn't be much resistance. Hence the graphite acts as a lubricant.
In contrast, most of the carbon atoms in a piece of diamond would be connected to each other. Unlike the sheets in graphite, in a diamond there are almost no moving parts. Also, the forces between neighboring carbon atoms are very strong. When an external force acts on a chunk of diamond, the carbon atoms would barely move. Hence, the structure appears to be very rigid. That gives diamond its abrasive properties.
Answer : The partial pressure of the 
in the tank in psia is, 32.6 psia.
Explanation :
As we are given 75 % and 25 % 
in terms of volume.
First we have to calculate the moles of and .
Now we have to calculate the mole fraction of .
Now we have to calculate the partial pressure of the gas.
conversion used : (1 Kpa = 0.145 psia)
Therefore, the partial pressure of the in the tank in psia is, 32.6 psia.
Answer :
The number of bonding pairs of electrons around the hydrogen atom = 2
The number of lone pairs of electrons around the hydrogen atom = 0
Explanation :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.
In the Lewis-dot structure the valance electrons are shown by 'dot'.
The given molecule is, 
As we know that carbon has '4' valence electrons, hydrogen has '1' valence electrons and nitrogen has '5' valence electrons.
Therefore, the total number of valence electrons in = 1 + 4 + 5 = 10
According to Lewis-dot structure we conclude that, there are 8 number of bonding electrons and 2 number of non-bonding electrons.
The number of bonding pairs of electrons around the hydrogen atom = 2
The number of lone pairs of electrons around the hydrogen atom = 0
The mass of Copper electroplated is 68.76 g
<h3>What is electroplating?</h3>
The process of plating a metal onto another is known as electroplating.
It is often used to prevent corrosion of metal or for the decorative purposes
In this process, electric current is passed through an aqueous solution containing dissolved cations.
The dissolved cations are reduced developing a thin metal coating on the electrode.
At cathode,
Current, I = 14.5 A
Time, t = 4 hrs = 4×60×60 = 14400 sec
Charge, q = It = 14.5×14400= 208800 C
Copper metal deposited by 2×96487 C = 63.55 g
Copper metal deposited by 208800 C = 
= 68.76g
Hence, The mass of Copper electroplated is 68.76 g
Learn more about electroplating:
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