List of top Chemistry Questions

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

Give the IUPAC names of the following compounds:

(f) Cl₂CHCH₂OH

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.

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.

Write bond line formulas for, Isopropyl alcohol, 2,3-Dimethylbutanal, Heptan-4-one.

Indicate the σ and π bonds in the following molecules. \(C_6H_6, C_6H_{12}, CH_2Cl_2, CH_2=C=CH_2, CH3NO2, HCONHCH_3.\)

A certain particle carries 2.5 × 10^–16 C of static electric charge. Calculate the number of electrons present in it.

How many electrons in an atom may have the following quantum numbers?

1. n = 4, m_s = – \(\frac 12\)
2. n = 3, l = 0

Consider the reactions: 
(a) \(6 \,CO_2(g) + 6H_2O(l) \rightarrow C_6H_{12}O_6(aq) + 6O_2(g)\) 
(b) \(O_3(g) + H_2O_2(l) \rightarrow  H_2O(l) + 2O_2(g)\) 
Why it is more appropriate to write these reactions as: (a) \(6\,CO_2(g) + 12H_2O(l) \rightarrow  C_6H_{12}O_6(aq) + 6H_2O(l) + 6O_2(g)\) 
(b) \(O_3(g) + H_2O_2(l) \rightarrow H_2O(l) + O_2(g) + O_2(g)\) 
Also suggest a technique to investigate the path of the above (a) and (b) redox reactions.

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 mass of an electron is 9.1 × 10^–31 kg. If its K.E. is 3.0 × 10^–25 J, calculate its wavelength.

Calculate the wavelength of an electron moving with a velocity of \(2.05×10^7 \ ms^{–1}\).

Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

The electron energy in hydrogen atom is given by \(E_n = \frac {(–2.18×10^{–18})}{n^2} \ J\). Calculate the energy required to remove an electron completely from the n = 2 orbit. What is the longest wavelength of light in cm that can be used to cause this transition?

The Mn³⁺ ion is unstable in solution and undergoes disproportionation to give Mn²⁺ , MnO₂, and H⁺ ion. Write a balanced ionic equation for the reaction.

What is the energy in joules, required to shift the electron of the hydrogen atom from the first Bohr orbit to the fifth Bohr orbit and what is the wavelength of the light emitted when the electron returns to the ground state ? The ground state electron energy is –2.18×10^–11 ergs.

Justify giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic acid is the best reductant.

The compound AgF₂ is an unstable compound. However, if formed, the compound acts as a very strong oxidizing agent. Why?

Calculate the wavenumber for the longest wavelength transition in the Balmer series of atomic hydrogen.

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?

What is the minimum volume of water required to dissolve 1g of calcium sulfate at 298 K? (For calcium sulfate, K_sp is 9.1 × 10^–6).

How much energy is required to ionise a H atom if the electron occupies n = 5 orbit? Compare your answer with the ionization enthalpy of H atom (energy required to remove the electron from n = 1 orbit).