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:
A partial lunar eclipse occurs when the Earth moves between the Sun and Moon but the three celestial bodies do not form a straight line in space. When that happens, a small part of the Moon's surface is covered by the darkest, central part of the Earth's shadow, called the umbra.
Explanation:
The term that best described a 10 gram of KClO3 per 100 grams of water solution at 30 degree Celcius is Saturated. The solubility chart is needed for this work. If the solubility chart is drawn for KClO3, it will be observed that the proportion of KClO3 that is needed to dissolve in 100ml of water to make the solution saturated is 10 grams at 30 degree Celcius.
Answer: a
Explanation:
Industry uses only about 18% while the others use around 70-90% of water.
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