The most abundant noble gas in atmosphere is

• neon

• argon

• xenon

• krypton

The least stable hydride of 15th group elements is

• BiH₃

• NH₃

• AsH₃

• SbH₃

Which one of the following oxides of nitrogen dimerises into colourless is solid/ liquid on cooling?

• N₂O

• NO

• N₂O₃

• NO₂

Halogens exist in -1,+ 1, + 3, + 5 and 47 oxidation states. The halogen that exists only in -1 state is

• F

• Cl

• Br

• I

Among the oxyacids of phosphorus, the dibasic acid is

• H₃PO₃

• H₄P₂O₇

• H₂PO₂

• HPO₃

Which of the following is the correct method of preparation of methyl fluoride?

• CH₄ + HF →

• CH₃OH + HF →

• CH₄ + F₂ →

• CH₃Br + AgF →

Which of the following species can function both as oxidising as well as reducing agent?

• Cl^-

• ${\mathrm{ClO}}_4^{-}$

• ClO^-

• ${\mathrm{MnO}}_4^{-}$

Which of the following is used as an oxidiser in rocket propellants?

• Ammonium perchlorate

• Alcohol

• Acrylic rubber

• Polyurethane

299.

Concentrated sulphuric acid can be reduced by

• NaCl

• NaF

• NaBr

• NaOH

The element evolving two different gases on reaction with conc sulphuric acid is

• P

• C

• Hg

• S