D = 0.2 g / ml = 0.2 g / cm³
For example, density of steel is 7.85 g / cm³.
Density of pure water is 1.0 g/cm³. An object which has a density < 1.0 g/cm³ will float in water.
Answer: Material that has a density of 0.2 g/ml ( 0.2 g/cm³ ) is good for making couch cushions.
Sodom chloride is an ionic compound.
<h3>What is sodium chloride?</h3>
Sodium chloride is a compound that is formed by the combination of sodium and chlorine atoms. The compound is ionic as the ions of the atoms combine. Sodium looses one electron that can now be gained by chlorine.
Since the compound is ionic, it has a high melting and boiling point. This implies that the compound could melt as high as 801 degrees centigrade. The boiling point of the compound is much higher.
We can represent the compound using the ball and stick or the space filling model. The ball and stick model of sodium chloride has been shown in the image attached to this answer.
Learn more about ball and stick model:brainly.com/question/17217225
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Description of a nerve signal
The nerve signal, or action potential, is a coordinated movement of sodium and potassium ions across the nerve cell membrane. Here's how it works: As we discussed, the inside of the cell is slightly negatively charged (resting membrane potential of -70 to -80 mV).
Answer : The mass of sulfuric acid needed is
.
Solution : Given,
pH = 8.94
Volume of solution = 380 ml =

Molar mass of sulfuric acid = 98.079 g/mole
As we know,

![pOH=-log[OH^-]](https://tex.z-dn.net/?f=pOH%3D-log%5BOH%5E-%5D)
![5.06=-log[OH^-]](https://tex.z-dn.net/?f=5.06%3D-log%5BOH%5E-%5D)
![[OH^-]=0.00000871=8.71\times 10^{-6}mole/L](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D0.00000871%3D8.71%5Ctimes%2010%5E%7B-6%7Dmole%2FL)
Now we have to calculate the moles of
.
Formula used : 
![\text{ Moles of }[OH^-]=\text{ Concentration of }[OH^-]\times Volume\\\text{ Moles of }[OH^-]=(8.71\times 10^{-6}mole/L)\times (380\times 10^{-3}L)=3309.8\times 10^{-9}moles](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20%7D%5BOH%5E-%5D%3D%5Ctext%7B%20Concentration%20of%20%7D%5BOH%5E-%5D%5Ctimes%20Volume%5C%5C%5Ctext%7B%20Moles%20of%20%7D%5BOH%5E-%5D%3D%288.71%5Ctimes%2010%5E%7B-6%7Dmole%2FL%29%5Ctimes%20%28380%5Ctimes%2010%5E%7B-3%7DL%29%3D3309.8%5Ctimes%2010%5E%7B-9%7Dmoles)
For neutralization, equal number of moles of
ions will neutralize same number of
ions.
![\text{ Moles of }[OH^-]=\text{ Moles of }[H^+]=3309.8\times 10^{-9}moles](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20%7D%5BOH%5E-%5D%3D%5Ctext%7B%20Moles%20of%20%7D%5BH%5E%2B%5D%3D3309.8%5Ctimes%2010%5E%7B-9%7Dmoles)
As, 
From this reaction, we conclude that
2 moles of
ion is given by the 1 mole of 
moles of
ion is given by
moles of 
Now we have to calculate the mass of sulfuric acid.
Mass of sulfuric acid = Moles of
× Molar mass of sulfuric acid
Mass of sulfuric acid = 
Therefore, the mass of sulfuric acid needed is
.