Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Chemistry

Define conductivity for the solution of an electrolyte.

What is the role of desorption in the process of catalysis?

The reaction,

Cr₂O₃ + 2Al → Al₂O₃ + 2Cr

 (ΔG^θ = -421kJ) is thermodynamically feasible as is apparent from the Gibbs energy value.  Why does it not take place at room temperature?

Is it true that under certain conditions, Mg can reduce SiO₂ and Si can reduce MgO? What are those conditions?

Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?

Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.

Write chemical reactions taking place in the extraction of zinc from zinc blende.

State the role of silica in the metallurgy of copper.

The choice of a reducing agent in a particular case depends on thermodynamic factor. How far do you agree with this statement? Support your opinion with two examples.

Explain on the basis of valence bond theory that [Ni(CN)₄]²⁻ ion with square planar structure is diamagnetic and the [NiCl₄]²⁻ ion with tetrahedral geometry is paramagnetic.

Predict the number of unpaired electrons in the square planar [Pt(CN)₄]²⁻ ion.

Discuss the nature of bonding in the following coordination entity on the basis of valence bond theory:

[Fe(CN)₆]⁴⁻

[Cr(NH₃)₆]³⁺ is paramagnetic while [Ni(CN)₄]²⁻ is diamagnetic. Explain why?

Discuss the nature of bonding in the following coordination entity on the basis of valence bond theory:

[FeF₆]³⁻

Discuss the nature of bonding in the following coordination entity on the basis of valence bond theory:

[Co(C₂O₄)₃]³⁻

Discuss the nature of bonding in the following coordination entity on the basis of valence bond theory:

[CoF₆]³⁻

Why do we require artificial sweetening agents?

What are food preservatives?

Why is use of aspartame limited to cold foods and drinks?