31 Year NEET Previous Year Questions: The p-Block Elements - NEET MCQ

Cl₂ gas reacts with drys laked lime, Ca (OH)₂ at 40°C to give bleaching powder

Undecomposed AgBr forms a soluble complex with hypo

It is washed with water and the image is fixed

 (burns with blue light)

(burns with yellow light)

Chlorine does not react directly with oxygen.

Bleaching powder

NH₃ undergoes H-bonding and hence has the highest b.p. Among the remaining hydrides i.e. PH₃, AsH₃ and SbH₃ the b.p. increases as the size of the element increases and hence the magnitude of the van der Waal’s forces of attraction increases. Thus, PH₃ has the lowest b.p.

Magnesium and manganese are the metals that produce hydrogen with dilute nitric acid

As Nitrogen does not have d-orbital in its valence shell its maximum covalency is 3 while in the case of other elements the maximum covalency is 5.

Both white and red phosphorus are not soluble in CS₂ only white P is soluble.

Due to the absence of H-bonding, PH₃ has the lowest b.p. The boiling point of the Vth group hydrides is : BiH₃ > SbH₃ > NH₃ > AsH₃ > PH₃

Alkaline pyrogallol absorbs O₂ and oil of cinnamon absorbs O₃.

Air is liquified by making use of the jouleThomson effect (cooling by expansion of the gas). Water vapour and CO₂ are removed by solidification. The remaining constituents of liquid air i.e., liquid oxygen and liquid nitrogen are separated by means of fractional distillation (b.p. of O₂ = –183°C : b. P. of N₂ = – 195.8°C).

In case of nitrogen, d-orbitals are not available.

Bleaching action of chlorine is due to oxidation in presence of moisture. It is permanent

Colouring matter + | O | → colourless matter

Alkaline solution of pyrogallol absorbs oxygen quickly.

Oleum is H₂S₂O₇ ( H₂SO₄ + SO₃) which is obtained by dissolving SO₃ in H₂SO₄ and is called fuming sulphuric acid.

Aqueous solution of ammonia is obtained by passing NH₃ in H₂O which gives NH⁴⁺ and OH^– ions.

P₂O₅ have great affinity for water. The final product is orthophosphoric acid.

It is a tribasic acid all the three hydrogen atoms are ionisable. It forms three series of salts.

Pure nitrogen in the lab can be obtained by heating ammonium nitrate. Ammonium nitrate is not a stable compound it dissociate to give nitrogen.

Phosphorus pentoxide has great affinity for water. It forms ortho phosphoric acid on absorbing water

It is thus used as a powerful dehydrating or drying agent.

Nitrogen molecule is diatomic containing a triple bond between two N atoms,
Therefore, nitrogen molecule is formed by sharing six electrons.

Cane sugar is oxidised to oxalic acid

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N₂ molecule contains triple bond between N atoms having very high dissociation energy (946 kJ mol^–1) due to which it is relatively inactive.

Hypophosphorous acid (HPA), or phosphinic acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2. As it contains only one P-OH group, its basicity is one.

chloride reacts with dry slaked lime to form bleaching power.

the actual composition of bleaching power is

Bromide in the mother liquor is oxidised to Br₂ by Cl₂ which is a stronger oxidising agent.