Which one is correct( a )or( b )

Option D. 100N.

Explanation:

In the attached photo, W is the weight of the rod. We can thus, obtain the value of W as follow:

Clock wise moment = (Wx1) + (100x3)

Anti clockwise moment = 400 x 1

Clockwise moment = Anti clockwise moment

(W x 1) + (100x3) = 400 x 1

W + 300 = 400

Collect like terms

W = 400 – 300

W = 100N.

Therefore, the weight of the rod is 100N.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.