NEET

Which of the following species has the highest dipole moment ?

NH₃
PH₃
AsH₃
SbH₃

Solution

Order of dipole moment

NH₃ > PH₃> AsH₃ > SbH₃

(Based upon electronegativity)

Noble gases are used in discharge tubes to gives different colours. Reddish orange glow is due to

Ar
Ne
Xe
Kr

Solution

Neon gives a distinctreddish glow when used in either low-voltage neon glow lamps or in high voltage discharge tube.

Which of the following oxides will bet he least acidic?

As₄O₆
As₄O₁₀
P₄O₁₀
P₄O₆

Solution

Acidic strength of oxyacids increases with increase in oxidation number and on moving from top to bottom in a group acidic strength of oxides also decrease due to decrease in electronegativity down the group.

\(\overset{+5}{P_{4}O_{10}}> \overset{+3}{P_{4}O_{6}}> \overset{+5}{As_{4}O_{10}}> \overset{+3}{As_{4}O_{6}}\)

In which of the following, NH₄OH is not used?

Tollen’s reagent
Nessler’s reagent
Group reagent for the analysis of IV group basic radicals
Group reagent for the analysis of III group basic radicals

Solution

Potassium tetraiodo mercurate (II) (K₂HgI₄) dissolves in KOH solution to give Nessler’s reagent. Nessler’s reagent is used to test NH\(_{4}^{-}\) ions.

Which of the following statements regarding sulphur is incorrect?

S₂ molecule is paramagnetic.
The vapours at 200°C consists mostly of S₈rings.
At 600°C the gas mainly consists of S₂molecules.
The oxidation state of sulphur is never less than +4 inits compounds.

Solution

Oxidation state of sulphur varies from – 2 to +6 in its various compounds.

Which of the following has maximum number of lone pairs associated with Xe ?

XeF₄
XeF₆
XeF₂
XeO₃

Solution

Hence XeF₂ has maximum no. of lone pairs of electrons.

Regular use of which of the the following fertilizers increases the acidity of soil?

Ammonium sulphate
Potassium nitrate
Urea
Super phosphate of lime.

Solution

(NH₄)₂SO₄+ 2H₂O → 2H₂SO₄ + NH₄OH

H₂SO₄ being strong acid increases the acidity of soil.In case of potassium nitrate and super phosphate of lime on hydrolysis strong base also form along with strong acid on hydrolysis results into neutralisation.

Identify the incorrect statement among the following.

Br₂ reacts with hot and strong NaOH solution to give NaBr and H₂O.
Ozone reacts with SO₂ to give SO₃.
Silicon reacts with NaOH(aq) in the presence of air to give Na₂SiO₃ and H₂O.
Cl₂ reacts with excess of NH₃ to give N₂ and HCl

Solution

Chlorine reacts with excess of ammonia to produce ammonium chloride and nitrogen.

3Cl₂+ 8NH₃(excess) → 6NH₄Cl + N₂

In which of the following compounds, nitrogen exhibits highest oxidation state ?

N₂H₄
NH₃
N₃H
NH₂OH

Solution

Compound Oxidation number of nitrogen

N₂H₄= –2

NH₄ = –3

N₃H = –1/3

NH₂OH = –1

Which of the following oxide is amphoteric ?

SnO₂
CaO
SiO₂
CO₂

Solution

SnO₂ is an amphoteric oxide because it reacts with acids as well as with bases to form corresponding salts.

SnO₂+ 2H₂SO₄(conc) → Sn(SO₄)₂ + H₂O

SnO₂ + 2NaOH → Na₂SnO₄ + H₂O

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