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

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

467.

excess of PCl₅ reacts with concentrated H₂SO₄ giving

• chlorosulphuric acid

• sulphurous acid

• sulphury chloride

• thionyl chloride

The statement that is not correct is

• Hypophosphorous acid reduces silver nitrate to silver

• In solid state PCl₅ exists as [PCl₄]⁺ [PCl₆]^-

• Pure phosphine is non-inflammable

• Phosphorous acid on heating disproportionates to give metaphosphonic acid and phosphine

On heating with concentrated NaOH solution in an inert atmosphere of CO₂ white phosphorus gives a gas. Which of the following statement is incorrect about the gas?

• It is less basic than NH₃

• It is more basic than NH₃

• It is highly poisonous and has smell like rotten fish

• Its solution in water decomposes in the presence of light

${\mathrm{MSO}}_4 \stackrel{{\mathrm{NH}}_4\mathrm{OH}}{\to }\underset{\mathrm{White}}{\downarrow \mathrm{X}} \underset{\mathrm{Excess}}{\overset{{\mathrm{NH}}_4\mathrm{OH}}{\to }} \mathrm{Y}\stackrel{{\mathrm{H}}_2\mathrm{S}}{\to } \downarrow \mathrm{Z}$.Here, M and Z are

• Cu, ZnS

• Zn, ZnS

• Fe, FeS

• Al, Al₂S₃