Recent questions tagged s-block-elements

Description : what are the common physical features of alkali metals?

Last Answer : Ans. Large Atomic and ionic radii, Low ionization enthalpies, metallic character, low melting and boiling Point, form ionic bond, low density,show flame coloration ,photoelectric effect.

Description : Why are potassium and caesium, rather than lithium used in photoelectric cells ?

Last Answer : Ans. Potassium and caesium have much lower ionization enthalpy than that of lithium. As a result, these metals on exposure to light, easily emit electrons but lithium does not. Therefore, K and Cs rather than Li are used in photoelectric cells

Description : why sodium is less reactive than potassium?

Last Answer : Ans. The ionization enthalpy of potassium is less than that of sodium and the electrode potential of Potassium (-2.95 V) is more negative than that of sodium (-2.71 V) and hence sodium is less reactive than potassium.

Description : When a cation is highly polarizing ? Which alkali metal cation has the highest polarizing power ?

Last Answer : Ans. A cation is highly polarizing if its charge/size ratio is very high.Li+ has the highest polarizing power .

Description : Name the alkali metal which forms only the normal oxide on heating with air ?

Last Answer : Ans. Li.

Description : Name the alkali metal which shows diagonal relationship with Mg?

Last Answer : Ans.Li

Description : Why is sodium metal kept under kerosene oil ?

Last Answer : Ans. Sodium metal is highly reactive and combines with air forming sodium oxide.

Description : What are the raw material used for the manufacture of washing soda by solvay process ?

Last Answer : Ans. Nacl, CaCO3 and NH3

Description : Name the chief factor responsible for the anomalous behavior of lithium.

Last Answer : Ans. High polarizing power (charge/size ratio).

Description : What happens when KO2 reacts with water ?

Last Answer : Ans. 2 KO2 + 2H2O ------> 2 KOH + H2O2 + O2