List of top Chemistry Questions asked in CBSE Class XI

A 0.02M solution of pyridinium hydrochloride has pH = 3.44. Calculate the ionization constant of pyridine.
Predict if the solutions of the following salts are neutral, acidic or basic: NaCl, KBr, NaCN, NH4NO3, NaNO2 and KF
Fluorine reacts with ice and results in the change:
\(H_2O(s) + F_2{(g)} \rightarrow HF{(g)} + HOF{(g)}\) Justify that this reaction is a redox reaction.
The ionization constant of chloroacetic acid is 1.35 × 10–3. What will be the pH of 0.1M acid and its 0.1M sodium salt solution?
Write the formulae for the following compounds: 
(a) Mercury (II) chloride (b) Nickel (II) sulphate 
(c) Tin (IV) oxide (d) Thallium (I) sulphate 
(e) Iron (III) sulphate (f) Chromium (III) oxide
Suggest a list of the substances where carbon can exhibit oxidation states from -4 to +4 and nitrogen from -3 to +5.
While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why?
Depict the galvanic cell in which the reaction Zn(s) + 2Ag+ (aq) \(\rightarrow\)  Zn2+ (aq) + 2Ag(s) takes place, further show: 
  1. which of the electrode is negatively charged, 
  2. the carriers of the current in the cell, and
  3. individual reaction at each electrode.
Given the standard electrode potentials,
K+ /K = -2.93V,
Ag+/Ag = 0.80V, 
Hg2+/Hg = 0.79V 
Mg2+/Mg = -2.37V.
Cr3+/Cr = -0.74V
Arrange these metals in their increasing order of reducing power.
Calculate the wavelength, frequency and wave number of a light wave whose period is \(2.0×10^{–10}\ s\).
The ionic product of water at 310 K is 2.7 × 10–14. What is the pH of neutral water at this temperature?
Calculate the pH of the resultant mixtures: 
a) 10 mL of 0.2M Ca(OH)2 + 25 mL of 0.1M HCl 
b) 10 mL of 0.01M H2SO4 + 10 mL of 0.01M Ca(OH)2
c) 10 mL of 0.1M H2SO4 + 10 mL of 0.1M KOH
Arrange the following metals in the order in which they displace each other from the solution of their salts.
Al, Cu, Fe, Mg and Zn.
What is the number of photons of light with a wavelength of 4000 pm that provide 1J of energy?
Predict the products of electrolysis in each of the following:
  1. An aqueous solution of \(AgNO_3\) with silver electrodes
  2. An aqueous solution \(AgNO_3\) with platinum electrodes 
  3. A dilute solution of \(H_2SO_4\) with platinum electrodes 
  4. An aqueous solution of \(CuCl_2\) with platinum electrodes.
Refer to the periodic table given in your book and now answer the following questions:
  1. Select the possible non metals that can show disproportionation reaction. 
  2. Select three metals that can show disproportionation reaction
Consider the elements: \(Cs\), \(Ne\), \(I\) and \(F\)
  1. Identify the element that exhibits only negative oxidation state. 
  2. Identify the element that exhibits only postive oxidation state. 
  3. Identify the element that exhibits both positive and negative oxidation states.
  4. Identify the element which exhibits neither the negative nor does the positive oxidation state.
Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298K from their solubility product constants.Determine also the molarities of individual ions.
The total number of protons in $ 10\,g$ of calcium carbonate is $ (N_{0}=6.023\times 10^{23})$ :
Justify giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic acid is the best reductant.