Lithium possesses the highest melting point among alkali metals, a characteristic attributed to its small atomic size and strong metallic bonding. For Group 1 elements, the melting point decreases as atomic size increases, leading to weaker metallic bonds. The resulting order of melting points is:
• Lithium (Li): Highest melting point
• Sodium (Na)
• Potassium (K)
• Cesium (Cs): Lowest melting point
This observed trend illustrates the connection between atomic size and bond strength in metallic structures.
Which of the following statements are true?
A. Unlike Ga that has a very high melting point, Cs has a very low melting point.
B. On Pauling scale, the electronegativity values of N and C are not the same.
C. $Ar, K^{+}, Cl^{–}, Ca^{2+} and S^{2–}$ are all isoelectronic species.
D. The correct order of the first ionization enthalpies of Na, Mg, Al, and Si is Si $>$ Al $>$ Mg $>$ Na.
E. The atomic radius of Cs is greater than that of Li and Rb.
Choose the correct answer from the options given below: