List of top Chemistry Questions

What do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one example of each type.
What are hybridization states of each carbon atom in the following compounds? 
\(CH_2=C=O,\, CH_3CH=CH_2\),\((CH_3)_2CO, \,CH_2=CHCN, \,C_6H_6.\)
A certain particle carries 2.5 × 10–16 C of static electric charge. Calculate the number of electrons present in it.
If the velocity of the electron in Bohr’s first orbit is 2.19×106ms–1, calculate the de Broglie wavelength associated with it.
Indicate the σ and π bonds in the following molecules. \(C_6H_6, C_6H_{12}, CH_2Cl_2, CH_2=C=CH_2, CH3NO2, HCONHCH_3.\)
Distinguish between a sigma and a pi bond.
Write bond line formulas for, Isopropyl alcohol, 2,3-Dimethylbutanal, Heptan-4-one.
Calculate the oxidation number of Sulphur, chromium, and nitrogen in
\(H_2SO_5\), \(Cr_2O_7^{2−}\) and \(NO_3^−\). Suggest structure of these compounds. Count for the fallacy.
An ion with mass number 37 possesses one unit of negative charge. If the ion conatins 11.1% more neutrons than the electrons, find the symbol of the ion.
Using s, p, d notations, describe the orbital with the following quantum numbers.
  1. n=1, l=0
  2. n = 3, l=1
  3. n = 4, l =2
  4. n=4, l=3
Explain the formation of \(H_2\) molecule on the basis of valence bond theory.
  1. An atomic orbital has n = 3. What are the possible values of l and ml?
  2. List the quantum numbers (ml and l) of electrons for 3d orbital.
  3. Which of the following orbitals are possible?
    1p, 2s, 2p and 3f
Which of the following are isoelectronic species i.e., those having the same number of electrons?
\(Na^+, K^+, Mg^{2+}, Ca^{2+}, S^{2–}, Ar\)
Whenever a reaction between an oxidising agent and a reducing agent is carried out, a compound of lower oxidation state is formed if the reducing agent is in excess, and a compound of higher oxidation state is formed if the oxidising agent is in excess. Justify this statement giving three illustrations..
The velocity associated with a proton moving in a potential difference of 1000 V is 4.37×105 ms–1. If the hockey ball of mass 0.1 kg is moving with this velocity, calculate the wavelength associated with this velocity.
Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. Calculate the frequency (ν) and wavenumber (v) of the yellow light
Use molecular orbital theory to explain why the \(Be_2\) molecule does not exist.
Give the IUPAC names of the following compounds:
IUPAC names of compounds
(f) Cl2CHCH2OH
Identify the substance oxidised, reduced, oxidising agent and reducing agent for each of the following reactions:
  1. \(2AgBr (s) + C_6H_6O_2(aq) \rightarrow 2Ag(s) + 2HBr (aq) + C_6H_4O_2(aq)\)
  2. \(HCHO(l) + 2[Ag (NH_3)_2] ^+ (aq) + 3OH^ - (aq) \rightarrow 2Ag(s) + HCOO ^- (aq) + 4NH_3(aq) + 2H_2O(l)\)
  3. \(HCHO (l) + 2Cu^{ 2+}(aq) + 5 OH^ - (aq) \rightarrow Cu_2O(s) + HCOO ^- (aq) + 3H_2O(l)\)
  4. \(N_2H_4(l) + 2H_2O_2(l) \rightarrow N_2(g) + 4H_2O(l)\)
  5. \(Pb(s) + PbO_2(s) + 2H_2SO_4(aq) \rightarrow  2PbSO_4(s) + 2H_2O(l)\)
Which of the following represents the correct IUPAC name for the compounds concerned? 
(a) 2,2 Dimethylpentane or 2-Dimethylpentane 
(b) 2,4,7-Trimethyloctane or 2,5,7-Trimethyloctane 
(c) 2-Chloro-4 methylpentane or 4-Chloro-2-methylpentane 
(d) But-3-yn-1-ol or But-4-ol-1-yne.
Draw formulas for the first five members of each homologous series beginning with the following compounds.\((a) H–COOH (b) CH_3COCH_3 (c) H–CH=CH_2\)
Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:
\(CH_3COOH (l) + C_2H_5OH (l) ⇋ CH_3COOC_2H_5 (l) + H_2O (l) \)
  1. Write the concentration ratio (reaction quotient), Qc , for this reaction (note: water is not in excess and is not a solvent in this reaction)
  2. At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant. 
  3. Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium been reached?
If the electron's position is measured within an accuracy of + 0.002 nm, calculate the uncertainty in the electron's momentum. Suppose the momentum of the electron is \(\frac{h}{4\pi m}\) × 0.05 nm, is there any problem in defining this value?
Calculate the concentration of nitric acid in moles per litre in a sample which has a density, 1.41 g mL–1 and the mass per cent of nitric acid in it being 69%.
Which of the two, \(O+2NCH_2CH_2O^- \,or \,CH_3CH_2O^–\)is expected to be more stable and why?