I think its A because some scientist from the Department of Physics of Northeastern University found out that is not a part of Dalton's atomic theory.
Answer:
It is present in third period that's why its valance electrons are present in 3rd energy level.
Its atomic number is greater than lithium when compared in group wise.
There are more electrons in sodium to shield the outer valance electron thus nuclear attraction becomes weak and size increase.
Explanation:
The size of sodium is greater than lithium because atomic number of sodium is 11 and lithium is 3. Both are present in first group but sodium is present down to the lithium. As we move from top to bottom in a group atomic size increases with addition of electrons. The nuclear effect become weaker on valance electrons and atomic size increase. Same time shielding effect is also produces which shield the outer electrons from the influence of nucleus. While in case of lithium less electrons are present to shield the valance electrons.
As we note the position of both elements along period. The sodium is present in third period while lithium is present in second period. So, in case of sodium third energy level is involved. That's why its size is greater than lithium.
Experimental investigations<span> involve a process in which a "fair test" is designed and variables are actively manipulated, controlled, and measured in an effort to gather evidence to support or refute a </span>causal relationship<span>. Experimental investigations have a control group which does not receive any treatment. A classic example is "What is the effect of light color on plant growth?" In this experiment, the variable color of light is changed by the student. The student may compare red light to green light to natural light.
hope i helped ^_^</span>
