The period of the pendulum depends only on the length from the pivot to the "center of mass". So if the string has no mass, then the amount of mass on the end doesn't make any difference.
But if the pendulum is suspended on, say, a chain with mass, then the more mass on the bottom, the lower the center of mass is, and the longer the period is.
<h3><u>
Answer;</u></h3>
B) Not Balanced
B) Sodium
B) Not Equal
The equation is <em><u>not balanced</u></em> because the number of <em><u>sodium atoms</u></em> is <em><u>not equal</u></em> on both sides of the arrow.
<h3><u>Explanation;</u></h3>
- <em><u>According to the law of conservation of mass, the mass of reactants should always be the same as the mass of the products in a chemical equation.</u></em> Therefore, the number of atoms of each element in a chemical equation should always be the same on both sides of the equation, that is the side of reactants and side of products.
- Therefore,<u><em>any chemical equation requires balancing to ensure that the number of atoms of each element is equal in both sides of the equation</em></u>. Balancing is a try and error process that ensures that the law of conservation of mass holds.
- Thus, the balanced chemical equation is;
2Na + Cl2 → 2NaCl
Explanation :
Work is done when a force is applied to create a displacement on an object.
Thus, the work done depends on the two factors i.e.
(1) Applied force (F)
(2) Distance or displacement (d)
Mathematically, work done is 
It also depends on the angle between the force and the displacement.

For example,
A person carries a weight of 20 kg and lifts it on his head 1.5 m above the surface. So, the work done by him on the luggage will be:

or


So, 
Hence, the work done by him on the luggage is 294 Joules.
C and D are both possible.
But we have no idea which one is correct based on the given illustration, because you didn't give the illustration.
The first positively essential requirement is that
you absolutely have to know what 'a' and 'b' are.
I have no clue, so this is as far as I can go.