Given the reaction of N,N-dimethylaniline ('A') with NaNO2 and HX to form 'B', the correct statements are: (1) The electrophile involved in the reaction is NO+. (3) The reaction occurs at low temperature. (4) The product 'B' formed in the above reaction is p-nitroso compound at low temperature.
Explanation: The reaction is a diazotization reaction specific to tertiary aromatic amines. NaNO2 and HX generate the nitrosonium ion (NO+), which is the electrophile. Diazotization reactions are performed at low temperatures to prevent decomposition of intermediates. The product formed is a p-nitroso compound due to electrophilic aromatic substitution at the para position. Statement (2) is incorrect because the product is a p-nitroso compound, not an N-nitroso ammonium compound.
A bob of mass \(m\) is suspended at a point \(O\) by a light string of length \(l\) and left to perform vertical motion (circular) as shown in the figure. Initially, by applying horizontal velocity \(v_0\) at the point ‘A’, the string becomes slack when the bob reaches at the point ‘D’. The ratio of the kinetic energy of the bob at the points B and C is: