List of top Questions asked in CBSE CLASS XII

(c) Why osmotic pressure is a colligative property?
(A) An organic compound \( A \), molecular formula \( C_2H_6O \), oxidises with \( Cr_2O_7 \) to form a compound \( B \). Compound \( B \) on warming with iodine and aqueous solution of NaOH gives a yellow precipitate of compound \( C \). When compound \( A \) is heated with conc. \( H_2SO_4 \) at 413 K, it gives a compound \( D \), which on reaction with excess HI gives compound \( E \). Identify compounds \( A \), \( B \), \( C \), \( D \), and \( E \) and write chemical equations involved.
(b) Why pKₐ of aniline is more than that of methylamine?
(c) (i) Arrange the following in the increasing order of their basic character in an aqueous solution:
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The vector with terminal point A (2, -3, 5) and initial point B (3, -4, 7) is:

Accomplish the following conversions:

 (i) Nitrobenzene to benzoic acid 

(ii) Benzene to m-bromophenol 

(iii) Benzoic acid to aniline 

(iv) Aniline to 2,4,6-tribromofluorobenzene 

(v) Benzyl chloride to 2-phenylethanamine 

(vi) Chlorobenzene to p-chloroaniline 

(vii) Aniline to p-bromoaniline 

(viii) Benzamide to toluene 

(ix) Aniline to benzyl alcohol.

How will you bring about the following conversions in not more than two steps?
(i)Propanone to Propene 
(ii)Benzoic acid to Benzaldehyde
(iii)Ethanol to 3-Hydroxybutanal 
(iv)Benzene to m-Nitroacetophenone
(v)Benzaldehyde to Benzophenone
(vi) Bromobenzene to 1-Phenylethanol
(vii)Benzaldehyde to 3-Phenylpropan-1-ol
(viii)Benazaldehyde to a-Hydroxyphenylacetic acid
(ix)Benzoic acid to m-Nitrobenzyl alcohol
 

 

What will counting up to twelve and keeping still help us achieve?

Write equations of the following reactions: 
(i)Friedel-Crafts reaction–alkylation of anisole.
(ii)Nitration of anisole.

(iii)Bromination of anisole in ethanoic acid medium.
(iv)Friedel-Craft’s acetylation of anisole.

 

Write two different vectors having same magnitude.
What are the major components of seminal plasma?

Write two different vectors having the same direction.

For the differential equations, find the general solution:\(\frac {dy}{dx} =(1+x^2)(1+y^2)\)

A short bar magnet of magnetic moment m = 0.32 J T-1 is placed in a uniform magnetic field of 0.15 T. If the bar is free to rotate in the plane of the field, which orientation would correspond to its ( a ) stable, and ( b) unstable equilibrium? What is the potential energy of the magnet in each case?

Find the number of all onto functions from the set {1,2,3,… ,n) to itself.

List the attributes that populations but not individuals possess.
Why was Edla happy to see the gift left by the peddler?
Using the worksheet below, find out the error and its reason for the given ‘VLOOKUP’ syntax: % Table for worksheet \[ \begin{array}{|c|c|c|c|c|} S. No. & Product & Q1 Sales (\( \text{\rupee} \)) & Q2 Sales (\( \text{\rupee} \)) & Total Half Yearly Sales (\( \text{\rupee} \))
1 & H & 15000 & 30000 & 45000
2 & I & 18000 & 32000 & 50000
3 & J & 20000 & 29000 & 49000
4 & K & 23000 & 26000 & 49000
5 & L & 20000 & 30000 & 50000
6 & M & 24000 & 28000 & 52000
7 & N & 24000 & 28000 & 52000
\end{array} \] % Question details (i) = VLOOKUP (B1, B2 : E8, 2, 0)
(ii) = SQRT (VLOOKUP (B5, B8 : E8, 2, 0) – 10000)
(iii) = VLOOKUP (A2, A2 : A8, 2, 0)
(iv) = VLOOKUP (B2, B3, E4, 5, 0)
(v) = VLOOKUP (B2, A2 : E8, 0, 0)
(vi) = VLOOKUP (B2, B2, E8, 2, 0)/0
Explain ‘Sequential Codes’ and ‘Block Codes’ with examples.
How to use ‘Mark Common Formula Error’ in Excel? Explain.
State why do you need to change a chart? How can it be changed? Why is it said that changing a column chart to a pie chart is easy? Give reasons.
State the advantages of computerized accounting system.
Excel considers which of the following group of mathematical operations of equal importance?
How many rows are available in Excel 2007?
How are ‘absolute cell references’ and ‘mixed references’ identified in Excel?