Question

Identify the most stable species in the following set of ions giving reasons: $\overset{\text{+}}{C}H_{3}, \overset{\text{+}}{C}H_{2}Br, \overset{\text{+}}{C}HBr_{2}, \overset{\text{+}}{C}Br_{3}$

Answer 1

"Comparing all the carbon cations above, $^{ + }{ CH }_{ 3 }$ is the most stable species which has the least polarity. Whereas in all the other cations the Br atoms are there which increases the polarity due to the presence of electron withdrawing group Br.

So the order of increasing stability of the carbocations are as follows,  

$^{ + }{ CBr }_{ 3 }\quad <\quad ^{ + }{ CHBr }_{ 2 }\quad <\quad ^{ + }{ CH }_{ 2 }Br\quad <\quad ^{ + }{ CH }_{ 3 }$"

Answer 2

Explanation:

$A 2 cm cube of some substance has its upper face displayed by 0.15 cm due to a tangential force of 0.3 N while keeping the lower face fixed. Calculate the rigidity modulus of the substance.$