251.

Which of the following hydrogen bonds are strongest in vapour phase?

• HF..........HF

• HF..........HCl

• HCl..........HCl

• HF..........HI

Compound A and B are treated with dil. HCl separately. The gases liberated are Y and Z respectively. Y turns acidified dichromate paper green while Z turns lead acetate paper black. The compound A and B are respectively.

• Na₂CO₃ and NaCl

• Na₂SO₃ and Na₂S

• Na₂S

• Na₂SO₄

Fluorine reacts with dilute NaOH and forms a gaseous. product A. The bond angle in the molecule of A is

• 104°40'

• 103°

• 107°

• 109°28'

The number of $\mathrm{p\pi }-\mathrm{d\pi }$ 'pi' bonds present in XeO₃ and XeO₄ molecules, respectively are

• 3,4

• 4,2

• 2,3

• 3,2

The type of bonds present in sulphuric anhydride are

• $3\mathrm{\sigma } \mathrm{and} \mathrm{three} \mathrm{p\pi }-\mathrm{p\pi }$

• $3\mathrm{\sigma }, \mathrm{one} \mathrm{p\pi }-\mathrm{p\pi } \mathrm{and} \mathrm{two} \mathrm{p\pi }-\mathrm{p\pi }$

• $2\mathrm{\sigma } \mathrm{and} \mathrm{three} \mathrm{p\pi }-\mathrm{d\pi }$

• $2\mathrm{\sigma } \mathrm{and} \mathrm{two} \mathrm{p\pi }-\mathrm{d\pi }$

Which pair of oxyacids of phosphorus contains 'P - H' bonds?

• H₃PO₄, H₃PO₃

• H₃PO₅, H₄P₂O₇

• H₃PO₃, H₃PO₂

• H₃PO₂, HPO₃

$\mathrm{Cl}-\mathrm{P}-\mathrm{Cl}$ bond angles in PCl₅ molecule are

• 120° and 90°

• 60° and 90°

• 60° and 120°

• 120° and 30°

Hair dyes contain

• copper nitrate

• gold chloride

• silver nitrate

• copper sulphate

Which of the following compounds volatilises on heating?

• MgCl₂

• HgCl₂

• CaCl₂

• FeCl₃

AgCl dissolves in a solution of NH₃ but not in water because :

• NH₃ is a better solvent than H₂O

• Ag⁺ forms a complex ion with NH₃

• NH₃  is a stronger base than H₂O

• the dipole moment of water is higher than NH₃