The incorrect statement in respect of chromyl chloride test is

• formation of red vapours

• formation of lead chromate

• formation of chromyl chloride

• liberation of chlorine

The number of naturally occurring p block elements that are diamagnetic is

• 18

• 6

• 5

• 7

In Kjeldahl's method, ammonia from 5 g of food neutralizes 30 cm³ of 0.1 N acid. The percentage of nitrogen in the food is

• 0.84

• 8.4

• 16.8

• 1.68

In Ramsay and Rayleigh's isolation of noble gases from air, the nitrogen of the air is finally converted into

• NaNO₂ only

• NO and NO₂

• NaNO₃ only

• NaNO₂ and NaNO₃

A white crystalline salt A reacts with dilute HCl to liberate a suffocating gas B and also forms a yellow precipitate. The gas B turns potassium dichromate acidified with dilute H₂SO₄ to a green coloured solution C. A, B, C are respectively

• Na₂SO₃, SO₂, Cr₂(SO₄)₃

• Na₂S₂O₃, SO₂, Cr₂(SO₄)₃

• Na₂SO₂ , SO₂, Cr₂(SO₄)₃

• Na₂SO₄, SO₂, Cr₂(SO₄)₃

Molecules of a noble gas do not possess vibrational energy because a noble gas

• is monoatomic

• is chemically inert

• has completely filled shells

• is diamagnetic

277.

Which of the following is employed in flash tubes in photograph?

• Ar

• Ne

• Kr

• Xe

Which one of the following sets of ions represents the collection of isoelectronic species?

• K⁺, Cl^-, Mg²⁺, Sc³⁺

• Na⁺, Ca²⁺, Sc³⁺, F^-

• K⁺, Ca²⁺, Sc³⁺,Cl^-

• Na⁺, Mg²⁺, Al³⁺, Cl^-

When formic acid is heated with conc. H₂SO₄  the gas evolved is

• Only CO₂

• Only CO₂

• mixture of CO and CO₂

• a mixture of SO₂ and CO₂

excess of PCl₅ reacts with concentrated H₂SO₄ giving

• chlorosulphuric acid

• sulphurous acid

• sulphury chloride

• thionyl chloride