The ionization enthalpy of $Na^{+}$ formation from $Na_{(g)}$ is $495.8 \ kJ \ mol^{-1},$ while the electron gain enthalpy of $Br_{(g)}$ is $-325.0 \ kJ \ mol^{-1}$. Given the lattice enthalpy of $NaBr_{(s)}$ is $-728.4 \ kJ \ mol^{-1}$. The energy for the reaction $Na_{(g)} + Br_{(g)} \rightarrow NaBr_{(s)}$ is $(-) \dots \dots \dots \dots \dots \times 10^{-1} \ kJ \ mol^{-1}$.

Which of the following species does not exist?

What is an ionic bond? With two suitable examples,explain the difference between an ionic and a covalent bond.

Which of the following is the correct increasing order of $O-O$ bond length in $O_2$,$O_3$,and $H_2O_2$?

Which of the following statements is true with respect to $H_2O$,$NH_3$ and $CH_4$?
$A.$ The central atoms of all the molecules are $sp^3$ hybridized.
$B.$ The $H-O-H$,$H-N-H$ and $H-C-H$ angles in the above molecules are $104.5^{\circ}$,$107.5^{\circ}$ and $109.5^{\circ}$ respectively.
$C.$ The increasing order of dipole moment is $CH_4 < NH_3 < H_2O$.
$D.$ Both $H_2O$ and $NH_3$ are Lewis acids and $CH_4$ is a Lewis base.
$E.$ $A$ solution of $NH_3$ in $H_2O$ is basic. In this solution,$NH_3$ and $H_2O$ act as a Lowry-Bronsted base and acid respectively.
Choose the correct answer from the options given below:

Determine the correct $(T)$ and incorrect $(F)$ statements for the permanganate ion $(MnO_4^-)$:
$(a)$ $MnO_4^-$ contains $\sigma$ bonds.
$(b)$ $MnO_4^-$ contains $\pi$ bonds.
$(c)$ $MnO_4^-$ contains both $\sigma$ and $\pi$ bonds.
$(d)$ $MnO_4^-$ is paramagnetic.