Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Honey contains primarily ____________.

The vapour pressure of benzene at 30°C is 121.8 mm. By adding 15 g of non-volatile solute in 250 g of benzene, its vapour pressure is decreased to 120.2 mm. The molecular weight of solute is:

The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatile, nonelectrolyte solid weighing 0.5 g is added to 39.0 g of benzene (molar mass 78 g/mol). The vapour pressure of the solution then is 0.845 bar. What is the molecular mass of the solid substance?

The vapour pressure of pure benzene at 25°C is 640 mm Hg and that of solution of solute A is 630 mm Hg. The molality of a solution is:

The solubility of a solid in a liquid is significantly affected by temperature changes.

\[\ce{Solute + Solvent -> Solution}\]

The system being in a dynamic equilibrium must follow Le-chatelier’s principle.

Considering the Le-chatelier’s principle which of the following is correct?

At a particular temperature, the vapour pressures of two liquids A and B are respectively 120 and 180 mm of mercury. If 2 moles of A and 3 moles of B are mixed to form an ideal solution, the vapour pressure of the solution at the same temperature will be (in mm of mercury):

A solution containing 10 g per dm³ of urea (molecular mass = 60 g mol^–1) is isotonic with a 5% solution of a non-volatile solute. The molecular mass of this non-volatile solute is:

The vapour pressure of a solvent decreases by 10 mm of Hg when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of Hg?

The number of P–O–P bridges in the structure of phosphorus pentoxide and phosphorus trioxide are respectively:

The three important oxidation states of phosphorus are ____________.

In the preparation of chlorobenzene from aniline, the most suitable reagent is:

A Grignard reagent may be made by reacting magnesium with ____________.

Which of the following alkyl halides is used as a methylating agent?

Which one of the following produces acyl halide by treatment with PCl₅?

Lucas reagent is ____________.

Lucas test is used for the detection of _____________.

The compound which reacts fastest with Lucas reagent at room temperature is:

In the reduction \[\ce{R - CHO + H2 -> RCH2OH}\] the catalyst used is:

By which of the following methods alcohol can be prepared in excellent yield?

Which of the following are used to convert RCHO into RCH₂OH?

(i) H₂/Pd

(ii) LiAlH₄

(iii) NaBH₄

(iv) Reaction with RMgX followed by hydrolysis