For a first-order reaction A $$\to$$ P, the temperature (T) dependent rate constant (k) was found to follow the equation $$\log k = - (2000){1 \over T} + 6.0$$. The pre-exponential factor A and activation energy $$E_a$$, respectively, are

The spin only magnetic moment value (in Bohr magneton units) of Cr(CO)$$_6$$ is

In the following carbocation, H/CH$$_3$$ that is most likely to migrate to the positively charged carbon is :

The correct stability order of the following resonance structures is