Ncert Solutions Chemistry Class 11th

(a) Due to its the lowest ionization energy, Cs is considered as the most electropositive element.

(b) Lithium cannot be used in making photoelectric cells because out of all the alkali metals it has the highest ionization energy and thus cannot emit electrons when exposed to light.

(c) Due to smal

Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide.

The loosely held s-electron in the outermost valence shell of these elements makes them the most electropositive metals which readily give ions, M+ or M2+.

Li+ has maximum degree of hydration due to its small size and for this reason lithium salts are mostly hydrated.

Hydration energy decreases down the group from Be to Ba and lattice energy remains almost constant.

Lithium, sodium, potassium, rubidium, caesium and Francium are group I elements and collectively known as the alkali metals.

They are called as the alkali metals because they form hydroxides on reaction with water which are strongly alkaline in nature.

The ionic radius of Be²⁺ is estimated to be 31 pm; the charge/radius ratio is nearly the same as that of the Al³⁺ ion. Hence beryllium resembles aluminium in some ways. Some ofthe similarities are:

(i) Like aluminium, beryllium is not readily attacked by acids because of the presence of an oxide fil

(b) BaCl₂ < SrCl₂ < CaCl₂ 2

(c) Reason is wrong a statement. More negative is the electrode potential, higher is the tendency of the element to lose electrons and hence, stronger is the reducing agent.