Which of the following is the most stable cation?

Which of the following has maximum stability?

The correct stability order of carbocations is

In which of the following reactions does a rearrangement take place with a change in the carbon skeleton?

Arrange the following carbocations in increasing order of stability:
$1. \, (CH_3)_2 - \overset{+}{C} - CH_2 - CH_3$
$2. \, (CH_3)_3 - \overset{+}{C}$
$3. \, (CH_3)_2 - \overset{+}{C} H$
$4. \, CH_3 - \overset{+}{C} H_2$
$5. \, \overset{+}{C} H_3$

Which of the following molecules/species is the most stable?