Many people believe that the atomic number of the atom is the number of electrons in the atom. Describe when this is the case
2 answers:
Answer: The atomic number of the atom is the number of electrons in the atom only when the atom is neutral.
Explanation: For a neutral atom, the number of positive charges is equal to the number of negative charges and thus the atomic number is equal to the number of electrons or the number of protons.
But for a positive and a negative ion, the electrons are lost and gained respectively by that element and thus the number of electrons are not equal to the number of protons. Now atomic number is equal to the number of protons only. The number of electrons = number of protons - charge.
Example: For sodium , the atomic number is 11 and it has 11 electrons.
For sodium ion , the atomic number is 11 but the number of electrons = (11-1) = 10.
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Answer:
Explanation:
Given:
- mass of the object on a horizontal surface,
- coefficient of static friction,
- coefficient of kinetic friction,
- horizontal force on the object,
<u>Now the value of limiting frictional force offered by the contact surface tending to have a relative motion under the effect of force:</u>
where:
normal force of reaction acting on the body= weight of the body
As we know that the frictional force acting on the body is always in the opposite direction:
So, the frictional force will not be at its maximum and will be equal in magnitude to the applied external force and hence the body will not move.
so, the frictional force will be: