Some physical properties that a pencil would have is, color, density, texture, hardness (in this case the lead is soft). phase (liquid,solid gas), shape, size. physical properties describe the look and feel of a substance. I hope this helps
Answer:
anthropogenic sources like landfills, agricultural activities,coal mining and combustion and some sources are natural ones
Answer: The hydroxide concentration of this sample is 
Explanation:
When an expression is formed by taking the product of concentration of ions raised to the power of their stoichiometric coefficients in the solution of a salt is known as ionic product.
The ionic product for water is written as:
![K_w=[H^+]\times [OH^-]](https://tex.z-dn.net/?f=K_w%3D%5BH%5E%2B%5D%5Ctimes%20%5BOH%5E-%5D)
![7.7\times 10^{-14}=[H^+]\times [OH^-]](https://tex.z-dn.net/?f=7.7%5Ctimes%2010%5E%7B-14%7D%3D%5BH%5E%2B%5D%5Ctimes%20%5BOH%5E-%5D)
As ![[H^+]=[OH^-]](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D%5BOH%5E-%5D)
![2[OH^-]=7.7\times 10^{-14}](https://tex.z-dn.net/?f=2%5BOH%5E-%5D%3D7.7%5Ctimes%2010%5E%7B-14%7D)
![[OH^-]=3.85\times 10^{-7}](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D3.85%5Ctimes%2010%5E%7B-7%7D)
Thus hydroxide concentration of this sample is 
It’s a chemical reaction I guess? Or maybe it hits the water and unlike a solid and it being a liquid it goes into the water causing it to spread or something like that.
Answer : The percent difference between the ideal and real gas is, 4.06 %.
Explanation : Given,
Ideal pressure (true value) = 49.3 atm
Real pressure (measured value) = 47.3 atm
The formula used to calculate percent difference is :
Percent difference = 
Percent difference = 
Percent difference = 4.06 %
Therefore, the percent difference between the ideal and real gas is, 4.06 %.