List of top Questions asked in CBSE CLASS XII

Why second ionization enthalpies of chromium and copper are exceptionally higher than those of their neighbouring elements?
Write the unit of (i) second order reaction and (ii) zero order reaction.
Define Effective collision.
Indicate the type of isomerism exhibited by the following complex: $[Co(en)_3]Cl_3$
Define coordination number.
Assertion (A): Aromatic primary amines can be prepared by Gabriel phthalimide synthesis. Reason (R): Aryl halides do not undergo nucleophilic substitution with phthalimide ion. Choose the correct option:
Assertion (A): Glucose gets oxidized to six carbon gluconic acid on reaction with bromine water. Reason (R): The carbonyl group is absent in the open chain structure of glucose. Choose the correct option:
Assertion (A): The molecularity of the given reaction is 2. \[ 2\text{HI} \rightarrow \text{H}_2 + \text{I}_2 \] Reason (R): Two molecules of the reactants are involved in simultaneous collision between them. Choose the correct option:
Assertion (A): Zinc, cadmium and mercury are not considered as transition elements. Reason (R): These elements have completely filled $d$ orbitals in their ground state as well as in their common oxidation states. Choose the correct option:
Proteins are polymers of $\alpha$-amino acids which are joined to each other by:
Which of the following reactions is not explained by the open chain structure of glucose?
Identify the compound produced by the reduction of ethanenitrile with lithium aluminium hydride:
The base which is present in DNA but not in RNA is:
Which of the following molecule is chiral in nature?
Identify the correct increasing order of boiling points of the given compounds:
The correct IUPAC name of the complex [Pt(NH$_3$)$_2$Cl$_2$] is:
Which of the following is heteroleptic complex?
The order for the given reaction is: \[ \text{A} + 2\text{B} \rightarrow \text{Products} \] \[ \text{Rate} = k[\text{A}]^{1/2}[\text{B}]^{1} \]
Electronic configuration of chromium is:
Consider the following reaction: \[ \text{Zn}_{(s)} + \text{Ag}_2\text{O}_{(s)} + \text{H}_2\text{O}_{(l)} \rightarrow \text{Zn}^{2+}_{(aq)} + 2\text{Ag}_{(s)} + 2\text{OH}^-_{(aq)} \] Given: \[ E^\circ_{\text{Ag}^+/\text{Ag}} = 0.80 \text{ V} \] \[ E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \text{ V} \] \[ 1F = 96500 \text{ C mol}^{-1} \] $\Delta G^\circ$ for above reaction is:
Identify the correct statement:
p-Nitrotoluene with \(Br_2\) (heat)
Write the major product in the following reactions: (1) Chlorobenzene + Na/dry ether
Although chlorine shows strong −I effect, it is ortho–para directing in electrophilic aromatic substitution. Why?
Predict the alkene formed by dehydrohalogenation of 1-bromo-1-cyclohexylethane.