JEE Advanced levelOne or more correct optionsDifficulty 3 of 3sb011
Which of the following statements about solutions of alkali metals in liquid ammonia are correct?
AOn standing with an iron catalyst the solution forms the amide and hydrogen.
BThe concentrated bronze solution is diamagnetic.
CThe blue colour is due to the absorption of light by the ammoniated cation.
DThe dilute blue solution is paramagnetic.
Answer: A, B, D
The dilute solution contains unpaired ammoniated electrons and is paramagnetic, while in concentrated solution the electrons pair up and the solution is diamagnetic. Catalysed decomposition: 2M+2NHX32MNHX2+HX2. The colour is due to the ammoniated electron, not the cation, so the last statement is wrong.