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 _____.

The K_sp for the following dissociation is 1.6 × 10^–5

$$PbC{l_{2(s)}} \leftrightharpoons Pb_{(aq)}^{2 + } + 2Cl_{(aq)}^ - $$

Which of the following choices is correct for a mixture of 300 mL 0.134 M Pb(NO₃)₂ and 100 mL 0.4 M NaCl ?

The de Broglie wavelength of an electron in the 4th Bohr orbit is :