Science (English Medium) Class 11 - CBSE Question Bank Solutions for Chemistry

The fragrance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for the extraction of these oils from the flowers is ______.

If a liquid compound decomposes at its boiling point, which method (s) can you choose for its purification. It is known that the compound is stable at low pressure, steam volatile and insoluble in water.

By mistake, an alcohol (boiling point 97°C) was mixed with a hydrocarbon (boiling point 68°C). Suggest a suitable method to separate the two compounds. Explain the reason for your choice.

Assertion (A): Components of a mixture of red and blue inks can be separated by distributing the components between stationary and mobile phases in paper chromatography.

Reason (R): The coloured components of inks migrate at different rates because paper selectively retains different components according to the difference in their partition between the two phases.

You have a mixture of three liquids A, B and C. There is a large difference in the boiling points of A and rest of the two liquids i.e., B and C. Boiling point of liquids B and C are quite close. Liquid A boils at a higher temperature than B and C and boiling point of B is lower than C. How will you separate the components of the mixture. Draw a diagram showing set up of the apparatus for the process.

A liquid with high boiling point decomposes on simple distillation but it can be steam distilled for its purification. Explain how is it possible?

Despite their - I effect, halogens are o- and p-directing in haloarenes. Explain.

Suggest a route to prepare ethyl hydrogensulphate (CH₃ – CH₂ – OSO₂ – OH) starting from ethanol (C₂H₅OH).

An alkene ‘A’ contains three C – C, eight C – H σ bonds and one C – C π bond. ‘A’ on ozonolysis gives two moles of an aldehyde of molar mass 44 u. Write IUPAC name of ‘A’.

Calcium carbonate reacts with aqueous HCl to give CaCl₂ and CO₂ according to the reaction,

\[\ce{CaCO_{3(s)} + 2 HCl_{(aq)} → CaCl_{2(aq)} + CO_{2(g)} + H2O_{(l)}}\]

What mass of CaCO₃ is required to react completely with 25 mL of 0.75 M HCl?

Chlorine is prepared in the laboratory by treating manganese dioxide (MnO₂) with aqueous hydrochloric acid according to the reaction

\[\ce{4HCl_{(aq)} + MnO_{2(s)} → 2H2O_{(l)} + MnCl_{2(aq)} + Cl_{2(g)}}\]

How many grams of HCl react with 5.0 g of manganese dioxide?

Symbols `""_35^79"Br"` and `""^79"Br"` can be written, whereas symbols `""_79^35"Br"` and `""^35"Br"` are not acceptable. Answer briefly.

The quantum numbers of six electrons are given below. Arrange them in order of increasing energies. If any of these combination(s) has/have the same energy lists:

1. n = 4, l = 2, m_l = –2 , m_s = - 1/2
2. n = 3, l = 2, m_l= 1 , m_s = +1/2
3. n = 4, l = 1, m_l = 0 , m_s = +1/2
4. n = 3, l = 2, m_l = –2 , m_s = –1/2
5. n = 3, l = 1, m_l = –1 , m_s= +1/2
6. n = 4, l = 1, m_l = 0 , m_s = +1/2

How many sub-shells are associated with n = 4?

How many electrons will be present in the sub-shells having m_s value of - 1/2 for n = 4?

Describe the hybridisation in case of PCl₅. Why are the axial bonds longer as compared to equatorial bonds?

Explain the physical significance of Van der Waals parameters.

Knowing the properties of H₂O and D₂O, do you think that D₂O can be used for drinking purposes?

Match the species in Column I with the geometry/shape in Column II.

What is \[\ce{SI}\] unit of viscosity coefficient (η)?