The chalk particles embed themselves into the small pores on the surface.
Although a chalkboard seems smooth to the touch, it is quite rough at the microscopic level, with <em>pores</em> that reach below the surface.
When you drag chalk across the board, friction causes small particles of chalk to rub off onto the surface.
If you leave the markings for a long time, some of the chalk particles will work their way into the pores.
A brush will remove the surface particles, but <em>it will not be able to get at the particles in the pores</em>.
Answer:
1.37cm
Explanation:
It's less than 1.4cm but more than 1.3cm. It's also more than 1.35cm so I guess the best answer would be 1.37cm or round up to 1.4cm
Heavy rainfall causes a landslide. Hence, option A is correct.
<h3>What is a landslide?</h3>
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope.
Water can trigger landslides and mudslides because it alters the pressure within the slope, which leads to slope instability.
Consequently, the heavy water-laden slope materials (soil, rock, etc.) will succumb to the forces of gravity.
Hence, option A is correct.
Learn more about the landslide here:
brainly.com/question/16151931
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Anything greater that 7 is a base....so 13 would be a very strong base for example a drain cleaner. Hopefully this is what you are looking for.
