List of top Questions asked in CBSE Class XI

Explain ETS.
The skeletal structure of CH3COOH as shown below is correct, but some of the bonds are shown incorrectly. Write the correct Lewis structure for acetic acid.
The skeletal structure of CH3COOH
Explain the process of inspiration under normal conditions.
Arrange the bonds in order of increasing ionic character in the molecules: LiF, K2O, N2, SO2 and ClF3.
Define electronegativity. How does it differ from electron gain enthalpy?
Write the expression for the equilibrium constant, Kc for each of the following reactions: 
  1. \(2NOCl (g) ⇋ 2NO (g) + Cl_2 (g)\)
  2. \(2Cu(NO_3)_2 (s) ⇋ 2CuO (s) + 4NO_2 (g) + O_2 (g)\)
  3. \(CH_3COOC_2H_5(aq) + H_2O(l) ⇋ CH_3COOH (aq) + C_2H_5OH (aq)\)
  4. \(Fe^{3+} (aq) + 3OH^– (aq) ⇋ Fe(OH)_3 (s)\)
  5. \(I_2 (s) + 5F_2 ⇋ 2IF_5\)
Write the significance/applications of dipole moment.
Find out the value of \(K_c\) for each of the following equilibria from the value of \(K_p\): 
  1. \(2NOCl (g) ⇋ 2NO (g) + Cl_2 (g); \ K_p= 1.8 × 10^{–2}\  at \ 500\ K\)
  2. \(CaCO_3 (s) ⇋ CaO(s) + CO_2(g); \ K_p= 167 \ at \ 1073\  K\)
Use Lewis symbols to show electron transfer between the following atoms to form cations and anions:
  1. K and S 
  2. Ca and O 
  3. Al and N.
What is the difference between lymph and blood?
Explain the important aspects of resonance with reference to the \(CO_3^{2-}\) ion.
Although geometries of NH3 and H2O molecules are distorted tetrahedral, bond angle in water is less than that of ammonia. Discuss.
Discuss the shape of the following molecules using the VSEPR model: 
BeCl2, BCl3, SiCl4, AsF5, H2S, PH3
Define octet rule. Write its significance and limitations.
How does cytokinesis in plant cells differ from that in animal cells?
Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidizing property is:
Describe the evolutionary change in the pattern of heart among the vertebrates.
At a certain temperature and total pressure of 105 Pa, iodine vapour contains 40% by volume of \(\text {I}\) atoms
\( I_2 (g) ⇋ 2I (g)\)
Calculate Kp for the equilibrium.
Distinguish cytokinesis from karyokinesis.
Considering the elements B, C, N, F, and Si, the correct order of their non-metallic character is:
Considering the elements B, Al, Mg, and K, the correct order of their metallic character is:
Which of the following statements related to the modern periodic table is incorrect?
What is Kc for the following equilibrium when the equilibrium concentration of each substance is: [SO2]= 0.60 M, [O2] = 0.82 M and [SO3] = 1.90 M ?
\(2SO_2(g) + O_2(g) ⇋ 2SO_3(g)\)
Differentiate between :
(a) Racemose and cymose inflorescence
(b) Apocarpous and syncarpous ovary
How is a pinnately compound leaf different from a palmately compound leaf?