Periodic Table and Elements

Atomic density is the number of atoms of a given type per unit volume of the material.   

The electron affinity (EA) of an element is defined as the energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion. Electron affinities are more difficult to measure than ionisation energies and are usually less accurately known. Electron affinities are large and negative for elements such as fluorine and oxygen, and small and positive for metals.

Each ion has 10 electrons For F^-, Z = 9 A = 19 n = 10 For Na⁺, Z = 11, A = 23, n = 12 For Mg²⁺, Z = 12 A = 24 n = 12 For O^2-, Z = 8 A = 16 n = 8

Electropositivity increases down a group and decreases across a period. Among the choices, potassium (an alkali metal) is the most electropositive.

Lithium shows a diagonal relationship with magnesium due to similar ionic sizes and charge-to-size ratios.

Sodium is the most abundant alkali metal in the Earth's crust, primarily found in minerals like halite (sodium chloride).

Alkali metals have a single electron in their outermost shell, making them highly reactive as they readily lose this electron to achieve a stable configuration. Because of this high reactivity, they react instantly with moisture and oxygen in the atmosphere, preventing them from existing in a free state.

Group 1 elements like K need less ionization energy hence most readily to form cation.

Ionization energy is the energy required to remove electron from an atom in its ground state. The noble gases having completely filled outermost shell have no tendency to lose any electron. So, they have highest ionisation energy.

The size of P atom is larger than N because when we go from period 2 to period 3 a new shell is added which means there occurs an increase in atomic size (when we move down a group).

Sodium is located in Group 1 of the periodic table, which is known as the alkali metal group.

Iodine is a chemical element in Group 17 of the periodic table, which is the halogen group.

Cobalt is a chemical element with the symbol Co and atomic number 27. It is located in the d-block of the periodic table, classifying it as a transition metal.

In this option statement 1 is said to be incorrect which is true as alkali metals get easily oxidized and not reduced by donating electrons from outermost shell and statement 2 is said to be correct which is true as alkali metals possess low value of ionization enthalpy.

Unlike expected order of first ionization enthalpies (IE₁) i.e., B > Al > Ga, the actual order of IE₁ is B > Ga > Al. Because of small atomic size and greater effective nuclear charge, the valence electrons of Ga are held more tightly than Al. Hence, IE₁ of Ga is more than that of Al.