Chemistry - Complete s-block Question with Solution | TestHub

A is true: calcium, strontium and barium give brick-red, crimson and apple-green flame colours, respectively.

B is true: small $\mathrm{B}{\mathrm{e}}^{2+}$ strongly polarises $\mathrm{C}{\mathrm{O}}_3^{2-}$.

Thermal stability increases as cation size increases down the group.

C is false: lithium has the highest first ionisation enthalpy among the alkali metals, so gaseous lithium atoms are not the strongest electron donors.

D is true: strong hydration of $\mathrm{L}{\mathrm{i}}^{+}$ makes $E^{\circ }(\mathrm{L}{\mathrm{i}}^{+}/Li)$ very negative.

In aqueous solution lithium is a stronger reducing agent than caesium.

Options A, B and D are correct.