Science (English Medium) कक्षा १२ - CBSE Important Questions

Write the type of magnetism observed when the magnetic moments are aligned in parallel and anti-parallel directions in unequal numbers.

Which stoichiometric defect decreases the density of the crystal?

Explain ionic solids are hard and brittle.

Define Molarity (M).

Write one difference in Coagulation and Peptization

Based on the nature of intermolecular forces, classify the following solids:

Sodium sulphate, Hydrogen

What happens when CdCl₂ is doped with AgCl?

How will you convert the following in not more than two steps:

Benzoic acid to Benzaldehyde

How will you convert the following in not more than two steps:

Acetophenone to Benzoic acid

30 g of urea (M = 60 g mol⁻¹) is dissolved in 846 g of water. Calculate the vapour pressure of water for this solution if vapour pressure of pure water at 298 K is 23·8 mm Hg.

What is meant by negative deviation from Raoult's law? Give an example. What is the sign of ∆_mixH for negative deviation?

Calculate the mass of NaCl (molar mass = 58.5 g mol⁻¹) to be dissolved in 37.2 g of water to lower the freezing point by 2°C, assuming that NaCl undergoes complete dissociation. (K_f for water = 1.86 K kg mol⁻¹)

Account for the following :

H₂S has lower boiling point than H₂O.

Which of the two components of starch is water soluble?

Define an ideal solution and write one of its characteristics.

Account for the following:

PCl₅ is more covalent than PCl₃.

Some liquids on mixing form 'azeotropes'. What are 'azeotropes'?

State Henry's Law. What is the effect of temperature on the solubility of a gas in a liquid?

What type of intermolecular attractive interaction exists in the pair of methanol and acetone?

State Raoult's law for the solution containing volatile components. What is the similarity between Raoult's law and Henry's law?