Oxyacids of phosphorus and the starting materials for their preparation are given below.

Oxyacid	Materials for preparation
A. H3PO2	i. Red P + alkali
B. H3PO3	ii. P4O10 + H2O
C. H3PO4	iii. P2O3 + H2O
D. H4P2O6	iv. White P + alkali

Choose the correct answer from the codes given below

• A - iv; B - iii; C - ii; D - i

• A - i; B - iii; C - ii; D - iv

• A - iv; B - iii; C - i; D - ii

• A - ii; B - iii; C - i; D - iv

Which halide of magnesium has highest ionic character?

• Chloride

• Bromide

• Iodide

• Fluoride

873.

The reaction takes place in two steps as

$$\begin{gathered} \left(\mathrm{i}\right) {\mathrm{NO}}_2\mathrm{Cl}\left(\mathrm{g}\right) \stackrel{{\mathrm{k}}_1}{\to } {\mathrm{NO}}_2\left(\mathrm{g}\right) + \mathrm{Cl}\left(\mathrm{g}\right) \\ \left(\mathrm{ii}\right) {\mathrm{NO}}_2\mathrm{Cl}\left(\mathrm{g}\right) +\mathrm{Cl}\left(\mathrm{g}\right) \stackrel{{\mathrm{k}}_2}{\to } {\mathrm{NO}}_2\left(\mathrm{g}\right) + \mathrm{Cl}\left(\mathrm{g}\right) \end{gathered}$$

Identify the reaction intermediate.

• NO₂Cl (g)

• NO₂(g)

• Cl₂(g)

• Cl(g)

What is the highest oxidation state exhibited by group 17 elements?

• +1

• +3

• +5

• +7

Brown ring test is used for detection of which radical?

• Ferrous

• Nitrite

• Nitrate

• Ferric

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