1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Deffense [45]
3 years ago
5

Chalk markings cannot be easily rubbed off from a black board if kept for a long time.why?

Chemistry
1 answer:
snow_tiger [21]3 years ago
3 0

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>.

You might be interested in
Why do the particles of objects have both kinetic and potential energy?  
OLEGan [10]
The particles of objects have both kinetic and potential energy because these forces are drive by the force of motion or stillness of an object. Potential energy is the a type of energy which an object possess however without motion. Kinetic energy in the other hand, is the energy in motion or if the object moves along from one space to another with respect to time. They both have these two energies by the presence of atoms in these entities.



3 0
3 years ago
Pierce conducts an experiment in which waves collide in a way that the energy increases, which means that has occurred
Vikki [24]
<h2>Answer:</h2>

It means the waves collides and constructive interference occurred.

<h3>Explanation:</h3>

If the two waves coming from the opposite direction collide with each other, there are two way of their interference.

  • Constructive interference: An interference which results in the increase in energy. And it is when crust of a wave comes on the crust of second wave.
  • Destructive interference: An interference which results in decrease in energy of the resulting wave and colliding waves cancel the result of each other.

Hence in experiment there will be constructive interference.

8 0
3 years ago
Read 2 more answers
The formulas for elements never contain a subscript true or not true
Andru [333]
The answer should be false. Elements contain only one atom.
7 0
3 years ago
Select multiple choices.<br><br> Thank you
AnnZ [28]
D, systems of writing
4 0
3 years ago
A piece of lithium is placed on the surface of some water in a beaker. hydrogen is given off. Lithium hydroxide is formed. What
Gala2k [10]
<span>A piece of lithium is placed on the surface of some water in a beaker. Hydrogen is given off and Lithium hydroxide is formed. The word equation would be as follows:
</span>

lithium<span> + </span>water<span>→ </span>lithium hydroxide<span> + </span>hydrogen

Hope this answers the question. Have a nice day.
8 0
3 years ago
Other questions:
  • Kyle is swinging at the playground. As he moves from the top of the swing to the bottom he will _____.
    9·1 answer
  • Select all that apply. what intermolecular forces stabilize a lipid bilayer?
    14·1 answer
  • How many grams of Cl2 are in 1.20 x 1024 Cl atoms?
    7·1 answer
  • Man's scientific theories are often in correct because his knowledge is​
    13·1 answer
  • What energy resource can be used instead of fossil fuel
    12·1 answer
  • How many milliliters of a 2.5% w/v chlorpromazine hydrochloride injection and how many milliliters of 0.9% w/v sodium chloride i
    13·1 answer
  • The Xs show the location of beanbags a student tossed at a target. The
    8·2 answers
  • What is reduced in the reaction below?
    5·1 answer
  • NO LINKSSS PLEASE!!!
    9·2 answers
  • Given the unbalanced equation:
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!