List of top Questions asked in CBSE Class XI

Write the resonance structures for SO3 , NO2 and NO3-
How many words, with or without meaning, can be formed using all the letters of the word EQUATION at a time so that the vowels and consonants occur together?
The concentration of sulphide ion in 0.1M HCl solution saturated with hydrogen sulphide is 1.0 × 10–19 M. If 10 mL of this is added to 5 mL of 0.04 M solution of the following: FeSO4, MnCl2, ZnCl2 and CdCl2. in which of these solutions precipitation will take place?
The story is divided into pre-War and post-War times. What hardships do you think the girl underwent during these times?
Have you known someone like the author’s grandmother? Do you feel the same sense of loss with regard to someone whom you have loved and lost?
In the alkane \( H_3C-CH_2-C(CH_3)_2-CH_2-CH(CH_3)_2\) , identify 1°,2°,3° carbon atoms and give the number of H atoms bonded to each one of these.
Using Binomial Theorem, evaluate \((102)^5\).
Evaluate\( ( √3 +√2) ^6 - ( √3 -√2) ^6.\)

A rain drop of radius 2 mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey ? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 10 m s–1 ?

Enthalpies of formation of CO(g), CO2(g), N2O(g) and N2O4(g) are –110, – 393, 81 and 9.7 kJ mol-1 respectively. Find the value of ∆rH for the reaction.
\(N_2O_4(g) + 3CO(g) → N_2O(g) + 3CO_2(g)\)
Balance the following redox reactions by ion-electron method: 
(a)MnO4- (aq) + I - (aq) → MnO2(s) + I2(s) (in basic medium)
(b) MnO4- (aq) + SO2(g) → Mn2+(aq) +HSO4- (aq) (in acidic solution)
(c) H2O2(aq)+Fe2+(aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O72-+ SO2(g) → Cr3+ (aq) +SO42- (aq) (in acidic solution)
At 700 K, equilibrium constant for the reaction:
\(H_2 (g) + I_2 (g) ⇋ 2HI (g)\)
is 54.8. If 0.5 mol L–1 of HI(g) is present at equilibrium at 700 K, what are the concentration of H2(g) and I2(g) assuming that we initially started with HI(g) and allowed it to reach equilibrium at 700 K?
Find the mean deviation about the mean for the data 4, 7, 8, 9, 10, 12, 13, 17.

Find the mean deviation about the mean for the data 38, 70, 48, 40, 42, 55, 63, 46, 54, 44.

Find the mean deviation about the median for the data.13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17.
How many 3-digit numbers can be formed from the digits 1, 2, 3, 4 and 5 assuming that. 
(i) repetition of the digits is allowed?
(ii) repetition of the digits is not allowed ?
If \((\frac {x}{3}+1, \frac {y-2}{3}) = (\frac {5}{3}, \frac {1}{3})\), Find the value of x and y.
How many 3-digit even numbers can be formed from the digits 1, 2, 3, 4, 5, 6 if the digits can be repeated?
How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

Find the radian measures corresponding to the following degree measures (i) 25° (ii) - 47° 30' (iii) 240° (iv) 520°

Find the degree measures corresponding to the following radian measures \((\text{Use }π=\frac{22}{7}).\)

\(\text{(i) }\frac{11}{16} \,\text{(ii)} -4 \,\text{(iii)}\,\frac{5π}{3}\, \text{(iv)}\, \frac{7π}{6}.\)

A coin is tossed 3 times and the outcomes are recorded. How many possible outcomes are there?
If the set A has 3 elements and the set B = {3, 4, 5}, then find the number of elements in (A x B)?
If G = {7, 8} and H = {5, 4, 2}, find G x H and H x G.
Given 5 flags of different colours, how many different signals can be generated if each signal requires the use of 2 flags, one below the other?