Yes of course.
Wearing down of pencil lead is a physical change because the substance is still the same (graphite), just in a different form (smaller pieces). No new substances are formed during the process, making it reversible by simply sharpening the pencil to create a new point.
No, an isothermal process is not necessarily internally reversible.
The pointed end of a pencil where the graphite or lead is located is called the pencil tip or pencil point.
Pencil Circuts
Yes, the entropy of the universe increases when a system undergoes a reversible process.
Wearing down of pencil lead is a physical change because the substance is still the same (graphite), just in a different form (smaller pieces). No new substances are formed during the process, making it reversible by simply sharpening the pencil to create a new point.
Although they both still have the same basic elements (i.e. pencil and lead vs water), there is a physical state change that occurs when you freeze water to make ice. Sharpening/shaving down a pencil only results in a difference of shape and size. It's about the same as ripping paper vs burning paper. Also, freezing water to make ice is a reversible change (you can melt ice to turn it back into water) and shaving a pencil is an irreversible change (you can't sharpen a pencil and then put the pencil shavings back onto the pencil.)
Yes, this change is reversible.
This is a reversible process.
You think probable to a reversible reaction.
reversible
no soil is not reversible.
reversible!
A Bunsen burner is an object: it is not a process of any kind.
reversible
Reversible.
reversible