Class 12 Chemistry 2020 Board Exam

The most common and stable oxidation state of a Lanthanoid is :
(a) + 2
(b) + 3
(c) + 4
(d) + 6

Out of the following, the strongest base in aqueous solution is
(a) Methylamine
(b) Dimethylamine
(c) Trimethylamine
(d) Aniline

The colligative property used for the determination of molar mass of polymers and proteins is :
(a) Osmotic pressure
(b) Depression in freezing point
(c) Relative lowering in vapour pressure
(d) Elevation is boiling point

Which of the following is affected by catalyst ?
(a) $\Delta$H
(b) $\Delta$G
(c) E${}_a$
(d) $\Delta$S

The compounds [Co(SO${}_4$) (NH${}_3$)${}_5$] Br and [Co(Br) (NH${}_3$)${}_5$] SO${}_4$ represent :
(a) optical isomerism
(b) linkage isomerism
(c) ionisation isomerism
(d) coordination isomerism

Predict the stereochemistry of the product formed if an optically active alkyl halide undergoes substitution reaction by S${}_N$1 mechanism.

Write the structures of the products formed when anisole is treated with HI.

What happens when
(a) Propanone is treated with methylmagnesium iodide and then hydrolysed, and
(b) Benzene is treated with CH${}_3$COCl in presence of anhydrous AlCl${}_3$ ?

The correct cell to represent the following reaction is :
Zn + 2Ag${}^{+}$ $⟶$ Zn${}^{2+}$ + 2Ag

(a) $2\text{Ag}\mid {\text{Ag}}^{+}\mid \mid \text{Zn}\mid {\text{Zn}}^{2+}$
(b) ${\text{Ag}}^{+}\mid \text{Ag}\mid \mid {\text{Zn}}^{2+}\mid \text{Zn}$
(c) $\text{Ag}\mid {\text{Ag}}^{+}\mid \mid \text{Zn}\mid {\text{Zn}}^{2+}$
(d) $\text{Zn}\mid {\text{Zn}}^{2+}\mid \mid {\text{Ag}}^{+}\mid \text{Ag}$

Out of the following transition elements, the maximum number of oxidation states are shown by
(a) Sc (Z = 21)
(b) Cr (Z = 24)
(c) Mn (Z = 25)
(d) Fe (Z = 26)