Neco 2017 Chemistry Question 46

A binary compound AB consists of element A (electronegativity 2.1) and element B (electronegativity 3.5). The measured A-B bond length is 150 pm. (i) Calculate the percent ionic character of the A-B bond using the formula \(\% \text{ionic}= \left(1-\exp\{-0.25(\Delta\chi)^2\}\right)\times100\), where \(\Delta\chi\) is the electronegativity difference. (ii) Classify the bond as non‑polar covalent, polar covalent or ionic, using the criteria: <20 % ionic → non‑polar covalent; 20-50 % → polar covalent; >50 % → ionic. (iii) If another compound AC with the same \(\Delta\chi\) has a bond length of 120 pm, estimate its percent ionic character assuming ionic character is inversely proportional to bond length.