Statement (I):} This statement is correct. SiO$_2$ (silicon dioxide) and GeO$_2$ (germanium dioxide) exhibit acidic behavior as they are covalent oxides. On the other hand, SnO (tin(II) oxide) and PbO (lead(II) oxide) are amphoteric in nature, meaning they can react with both acids and bases.
Statement (II): This statement is false. While catenation is indeed a key property responsible for the existence of multiple allotropic forms of carbon, $\pi$-$\pi$ bond formation is not the primary reason for carbon allotropy. Instead, the different hybridization states (sp$^3$, sp$^2$, and sp) and bonding patterns play a more critical role.
Conclusion: Statement I is true as it accurately describes the nature of the oxides, while Statement II is false because it incorrectly attributes carbon allotropy primarily to $\pi$-$\pi$ bond formation.
The portion of the line \( 4x + 5y = 20 \) in the first quadrant is trisected by the lines \( L_1 \) and \( L_2 \) passing through the origin. The tangent of an angle between the lines \( L_1 \) and \( L_2 \) is: