The central atom X uses $sp$ hybrid orbitals for bonding.

The molecule is linear.

The central atom X has no lone pairs of electrons.

The molecule must be polar if X and Y have different electronegativities.

${\rm{C}}{{\rm{l}}_2}{{\rm{O}}_6}$

${\rm{C}}{{\rm{l}}_2}{{\rm{O}}_7}$

${\rm{C}}{{\rm{l}}_2}{\rm{O}}$

${\rm{Cl}}{{\rm{O}}_2}$

${\rm{NO}}_3^ -$

${\rm{SO}}_3^{2 - }$

${\rm{BO}}_3^{3 - }$

${\rm{CO}}_3^{2 - }$

${\rm{Xe}}{{\rm{F}}_2},{\rm{IF}}_2^ -$

${\rm{N}}{{\rm{H}}_3},{\rm{B}}{{\rm{F}}_3}$

${\rm{CO}}_3^{2 - },{\rm{SO}}_3^{2 - }$

${\rm{PC}}{{\rm{l}}_5},{\rm{IC}}{{\rm{l}}_5}$

$X$

${X_2}$

${X_4}$

${X_5}$

$B{F_4}^ -$

$S{F_4}$

$Si{F_4}$

$Xe{F_4}$

13, 5

12, 6

14, 4

11, 7

$8{\rm{ }}and{\rm{ }}2$

$6{\rm{ }}and{\rm{ }}2$

$12{\rm{ }}and{\rm{ }}Zero$

$12{\rm{ }}and{\rm{ }}2$

CH≡CH and H₂C=C=CH₂

CO₂ and H₂C=C=CH₂

H₂C=CH₂ and CH₃-CH=CH₂

CH≡C-CH=CH₂ and O₂

${\rm{HF}} < HCl < HBr < HI$ : increasing acid strength

${\rm{N}}{{\rm{H}}_3} < P{{\rm{H}}_3} < As{{\rm{H}}_3} < Sb{{\rm{H}}_3}$ : increasing basic strength

${\rm{B}} < C < O < N$ : increasing first ionization enthalpy

${\rm{C}}{{\rm{O}}_2} < Si{{\rm{O}}_2} < Sn{{\rm{O}}_2} < Pb{{\rm{O}}_2}$ :increasing oxidising power

Boiling of ${{\rm{H}}_2}{\rm{O}}$

Melting of $KCN$

Boiling of ${\rm{C}}{{\rm{F}}_4}$

Melting of ${\rm{Si}}{{\rm{O}}_2}$