Question

Choose incorrect option for 3-d transition series:-

• A. Density increases from Ti to Cu
• B. first ionization enthalpy is highest for zinc
• C. enthalpy of atomization is lowest for manganese
• D. Cr${}^{2+}$ is a strong reducing agent

Answer 1

The correct option is C enthalpy of atomization is lowest for manganese

The decrease in metallic radius coupled with increase in atomic mass results in a general increase in the density of these elements. Thus, from titanium (Z = 22) to copper (Z = 29) the significant increase in the density.
For Zn, 1${}^{st}$ ionization enthalpy is higher because it represents an ionisation from the 4s level. Enthalpy of atomization is lowest for zinc due to absence of unpaired electrons not available for inter-atomic bonding. Cr${}^{2+}$ is reducing as its configuration changes from d${}^4$ to d${}^3$ , the latter having a half-filled t2g level.