Identify the correct statements from the following :
a) Change in hybridisation affects the electronegativity of carbon
b) The $p$ orbitals in ethene are mutually parallel
c) The number of $\sigma$ bonds in propyne is $6$
d) Electromeric effect is a permanent effect

Which of the following statements are not correct?
$a$. The energy of resonance hybrid structure is higher than that of the possible canonical structures of the molecule.
$b$. When inductive effect and electromeric effect operate in opposite directions,electromeric effect predominates.
$c$. When the $\pi$ electrons of the multiple bond are transferred to that atom to which the attacking reagent does not get attached,it is known as $+E$ effect.
$d$. The resonance structures with separation of opposite charges are more stable.

Which of the following electromeric effect representations is incorrect?

Fill in the blanks:
$(1)$ In $+E$ effect,$\pi$ electrons from a multiple bond migrate to the ........... .
$(2)$ In $-E$ effect,$\pi$ electrons from a multiple bond migrate to the ........... .
$(3)$ ........... and ........... increase stability.
$(4)$ ........... inductive effect increases the acidic strength and ........... inductive effect decreases the strength of $-COOH$.

Find the number of hyperconjugation structures in the isopropyl carbocation.

Represent the single electron movement of $CH_3-Cl$ bond.