An acidic buffer is obtained on mixing :

The Kjeldahl method of Nitrogen estimation fails for which of the following reaction products?

The complex that can show optical activity is :

The mechanism of S_N1 reaction is given as :
A student writes general characteristics based on the given mechanism as :
(a) The reaction is favoured by weak nucleophiles.
(b) R⁺ would be easily formed if the substituents are bulky.
(c) The reaction is accompanied by racemization.
(d) The reaction is favoured by non-polar solvents.