Which of these will produce the highest yield in Friedel Crafts reaction?

The molarity of HNO₃ in a sample which has density 1.4 g/mL and mass percentage of 63% is _____.
(Molecular Weight of HNO₃ = 63)

For the following reactions
$$A\buildrel {700K} \over \longrightarrow {\mathop{\rm Product}\nolimits} $$
$$A\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{catalyst}^{500K}} {\mathop{\rm Product}\nolimits} $$
it was found that E_a is decreased by 30 kJ/mol in the presence of catalyst.
If the rate remains unchanged, the activation energy for catalysed reaction is (Assume pre exponential factor is same):

The mass percentage of nitrogen in histamine is _____.