List of top Questions asked in CBSE CLASS XII

Write short notes on the following: 

(i) Carbylamine reaction 

(ii) Diazotisation 

(iii) Hofmann’s bromamide reaction 

(iv) Coupling reaction 

(v) Ammonolysis 

(vi) Acetylation 

(vii) Gabriel phthalimide synthesis.

Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heteroleptic.
Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.

\(FeSO_4\) solution mixed with\( (NH_4)_2SO_4 \) solution in\( 1:1\) molar ratio gives the test of \(Fe^{2+}\) ion but \(CuSO_4\) solution mixed with aqueous ammonia in \( 1:4 \) molar ratio does not give the test of \(Cu^{2+}\) ion. Explain why?

Explain the bonding in coordination compounds in terms of Werner’s postulates.

Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines. 

(i) (CH3 )2CHNH2 (ii) CH3 (CH2 )2NH2 (iii) CH3NHCH(CH3 )2 

(iv) (CH3 )3CNH2 (v) C6H5NHCH3 (vi) (CH3CH2 )2NCH3 (vii) m–BrC6H4NH2

Find the second order derivatives of the function
\(x^2+3x+2\)

Differentiate the functions with respect to x.
\(cos\ x^3.sin^2(x^5)\)

Differentiate the functions with respect to x.
\(sec(tan(\sqrt x))\)

Differentiate the functions with respect to x.
\(cos(sin\ x)\)

Compute the following:
\((i)\begin{bmatrix}a&b\\-b&a\end{bmatrix}+\begin{bmatrix}a&b\\b&a\end{bmatrix}\)
\((ii)\begin{bmatrix}a^2+b^2& b^2+c^2\\ a^2+c^2& a^2+b^2\end{bmatrix}+\begin{bmatrix}2ab& 2bc \\-2ac& -2ab\end{bmatrix}\)
\((iii)\begin{bmatrix}-1&4&-6\\ 8&5&16\\ 2&8&5\end{bmatrix}+\begin{bmatrix}12&7&6 \\8&0&5\\ 3&2&4\end{bmatrix}\)
\((iv)\begin{bmatrix}cos^2x& sin^2x\\ sin^2x& cos^2x\end{bmatrix}+\begin{bmatrix}sin^2x& cos^2x\\ cos^2x& sin2x\end{bmatrix}\)
Outline salient features of carbon cycling in an ecosystem
 
Express the following matrices as the sum of a symmetric and a skew-symmetric matrix:
\((i)\begin{bmatrix}3&5\\1&-1\end{bmatrix}\)
\((ii)\begin{bmatrix}6&-2&2\\ -2&3&-1\\ 2&-1&3\end{bmatrix}\)
\((iii)\begin{bmatrix}3&3&-1\\ -2&-2&1\\ -4&-5&2\end{bmatrix}\)
\((iv)\begin{bmatrix}1&5\\-1&2\end{bmatrix}\)
Define ecological pyramids and describe with examples, pyramids of number and biomass.

Briefly describe the following: 

(a) Transcription 

(b) Polymorphism 

(c) Translation 

(d) Bioinformatics
 

Which property of DNA double helix led Watson and Crick to hypothesise semiconservative mode of DNA replication? Explain.
Explain the following terms with example
(a) Co-dominance
(b) Incomplete dominance
How is sex determined in human beings?
Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross?
When a cross in made between tall plants with yellow seeds (TtYy) and tall plant with green seed (TtYy), what proportions of phenotype in the offspring could be expected to be
(a) Tall and green.
(b) Dwarf and green.
Maximise Z=-x+2y
subject to the constraints:
x≥3,x+y≥5,x+2y≥6,y≥0.
Minimise and Maximise Z=x+2y
Subject to x+2y≥100,2x-y≤0,2x+y≤200;x,y≥0.
Minimise and Maximise Z=5x+10y
Subject to x+2y≤120,x+y≥60,x-2y≥0,x,y≥0.
Using a Punnett square, work out the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.
Define and design a test - cross?