Given below are two statements :

Statement I : The first ionization enthalpy of Cr is lower than that of Mn .

Statement II : The second and third ionization enthalpies of Cr are higher than those of Mn .

In the light of the above statements, choose the correct answer from the options given below :

At $\mathrm{T}(\mathrm{K}), 100 \mathrm{~g}$ of $98 \% \mathrm{H}_2 \mathrm{SO}_4(\mathrm{w} / \mathrm{w})$ aqueous solution is mixed with 100 g of $49 \% \mathrm{H}_2 \mathrm{SO}_4(\mathrm{w} / \mathrm{w})$ aqueous solution. What is the mole fraction of $\mathrm{H}_2 \mathrm{SO}_4$ in the resultant solution?

(Given : Atomic mass $\mathrm{H}=1 \mathrm{u} ; \mathrm{S}=32 \mathrm{u} ; \mathrm{O}=16 \mathrm{u}$ ).

(Assume that temperature after mixing remains constant)

$$ \text { 3, 3-Dimethyl-2-butanol cannot be prepared by : } $$

$$ \text { Choose the correct answer from the options given below : } $$

$\mathrm{A}+2 \mathrm{~B} \longrightarrow \mathrm{AB}_2$

36.0 g of 'A' (Molar mass : $60 \mathrm{~g} \mathrm{~mol}^{-1}$ ) and 56.0 g of ' B ' (Molar mass : $80 \mathrm{~g} \mathrm{~mol}^{-1}$ ) are allowed to react. Which of the following statements are correct ?

A. 'A' is the limiting reagent.

B. $77.0 \mathrm{~g}$ of $\mathrm{AB}_2$ is formed.

C. Molar mass of $\mathrm{AB}_2$ is $140 \mathrm{~g} \mathrm{~mol}^{-1}$.

D. $15.0 \mathrm{~g}$ of A is left unreacted after the completion of reaction.

Choose the correct answer from the options given below :