The following mechanism has been proposed for the reaction of NO with Br₂ to form NOBr:
NO(g) + Br₂ (g) $$\leftrightharpoons$$ NOBr₂ (g)
NOBr₂ (g) + NO (g) $$\to$$ 2NOBr (g)
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is

The increasing order of the first ionization enthalpies of the elements B, P, S and F (lowest first) is :

Lanthanoid contraction is caused due to :

Which of the following statements is true?