Class 12th

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (i)

The 'Brown Ring Test' is an identification and conformation test of the nitrate ion  (NO₃^- ) using conc. H₂SO₄ and newly produced FeSO₄. Place the NO₃^-  containing sample in a test tube. Then, with gentle shaking, add conc H₂SO₄ dropwise, heat it briefly on a Bunsen burner, and add freshly made greenish FeSO4 Then, due to the creation of brown coloured  [Fe (H₂O)₅ (NO)]SO₄ complex, a brown ring forms in that test tube.

This is a Long Answer Type Question as classified in NCERT Exemplar

Sol:

$Giventhat:$
$\begin{array}{l} A=\{1,2,3\}\\ and R=\{(1,1),(2,2),\left(3,3\right),(1,2),\left(2,3\right),(1,3)\}\\ Here,1R1,2R2and3R3,So,Risreflexive.\\ 1R2but2\cancel{R}1or2R3but3\cancel{R}2,\\ So,Risnotsymmetric.\\ 1R1and1R2\Rightarrow 1R3,So,Ristransitive.\\ Hence,thecorrectansweris(a).\end{array}$

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (i)

The N-N sigma bond (single bond) is weaker than the P-P sigma bond (single bond) due to the smaller size of nitrogen which increases the interelectronic repulsions and thus making the bond weaker. 

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (ii)

The valence electrons of nitrogen are two 2s and three 2p. Nitrogen can make three covalent bonds by sharing its three 2p electrons. Consider the NH₃ molecule. The nitrogen atom, however, still contains a lone pair of electrons in the 2s orbital. It can take one bond by transferring these two electrons from the lone pair. Consider the NH₄⁺ molecule.

As a result, nitrogen can create four different bonds.

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (i)

The single N-N bond is weak because of high interelectronic repulsion of the non-bonding electrons, owing to the small bond length. As a result the catenation tendency is weaker in nitrogen that is why it does not show allotropy

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (ii)

On heating, lead nitrate decomposes into lead monoxide, nitrogen dioxide, and oxygen.

2Pb (NO₃)₂→2PbO + 4NO₂ + O₂.

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (iii)

H₃PO₂ has one O-H group and two P-H bonds

The existence of a P-H link gives phosphorus oxyacids their reducing characteristics. It has a strong proclivity for releasing protons. As a result, it demonstrates a decreasing nature.

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (iii) H₃PO₄

When it reacts with a metal atom, it can produce three different forms of salts, referred known as the three series of salts.

H₃PO₄ + Na→NaH₂PO₄

NaH₂PO₄ + Na→Na₂HPO₄

Na₂HPO₄ + Na→Na₃PO₄

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (iii)

When heated with concentrated NaOH in an inert CO₂ environment. It formsPH₃

P₄ + 3NaOH + 3H₂O→PH₃ + 3NaH₂PO₂

As we progress from the top to the bottom in a group, the basic character of hydrides reduces PH₃ is basic than NH₃.

This is a multiple choice answer as classified in NCERT Exemplar

Correct option is (iv)

The E-H bond dissociation energy of SbH₃ is the lowest among the aforementioned compounds, it easily releases H, making it a strong reducing agent. The greater the lowering agent, the weaker the E-H bond.