In the periodic table, horizontal rows are referred to as periods, representing the principal quantum number of the valence shell. Vertical columns are called groups, where elements share similar valence electron configurations and chemical properties.

The modern periodic table is arranged by increasing atomic number (making statement 4 true and 1 false). Statement 2 is false because the table is not based on atomic mass. Statement 3 is false because isotopes of the same element occupy the same position in the table, not adjacent groups. Thus, 1, 2, and 3 are false.

Non-metals are located on the right side of the periodic table, excluding hydrogen. Elements like sulfur (Group 16) and chlorine (Group 17) exhibit high electronegativity and non-metallic character, consistent with their position in the p-block on the right.

Group 2 elements, including beryllium, magnesium, calcium, strontium, barium, and radium, are collectively known as alkaline earth metals. They are reactive, electropositive, divalent metals that form basic oxides, which were historically referred to as 'earths'.

Dmitri Mendeleev is widely recognized as the first scientist to create a functional periodic table. In 1869, he arranged the elements by atomic mass and successfully predicted the existence and properties of several undiscovered elements, which provided strong evidence for his periodic law.

When electricity passes through sodium vapour, sodium atoms absorb energy, causing electrons to jump to higher energy levels. As these electrons return to their ground state, they release the absorbed energy as photons. For sodium, this transition corresponds to the yellow region of the visible spectrum (specifically the D-lines at 589.0 and 589.6 nm), resulting in the characteristic yellow light.

In Newland's Law of Octaves, he grouped elements with similar properties. Due to the limitations of his system, he placed Cobalt and Nickel in the same column as the halogens (Fluorine and Chlorine), which was a significant flaw in his classification scheme.

The element described is carbon, which is known for its unique ability to form stable, long chains (catenation). Carbon has an atomic number of 6, placing it in the second period of the periodic table. Its electronic configuration is 2, 4, indicating four valence electrons in the second shell.

Dmitri Mendeleev formulated his periodic law based on the observation that the properties of elements are a periodic function of their atomic masses. This was the standard classification method before the discovery of atomic numbers by Henry Moseley.

Newlands, Mendeleev, and Lothar Meyer were all pioneers in the development of the periodic classification of elements. Their work laid the foundation for the modern periodic table, which acts as a systematic 'table of contents' for all known chemical elements, organizing them based on their recurring properties and atomic structures.