Class 12th

This is a short answer type question as classified in NCERT Exemplar

PH₃ is insoluble in water and cannot create hydrogen bonds with it, it forms bubbles, whereas NH₃ dissolves because it is soluble in water and can form hydrogen bonds with it.

This is a short answer type question as classified in NCERT Exemplar

This is a short answer type question as classified in NCERT Exemplar

4NH₃ + 5O₂ 4NO + 6H₂O

This is a short answer type question as classified in NCERT Exemplar

SO₃ generates a dense fog of sulphuric acid that does not condense quickly, it is not absorbed directly in water to form H₂SO_4.

This is a long answer type question as classified in NCERT Exemplar

A = NH₄NO₂

B = N₂

C = NH₃

D = HNO₃ 

(i) NH₄NO₂→N₂ + 2H₂O

(ii) N₂ + 3H₂→2NH₃

(iii) 4NH₃ + 5O₂→4NO + 6H₂O

4NO + O₂→4NO₂

3NO₂ + H₂O→2HNO₃ + NO 

This is a long answer type question as classified in NCERT Exemplar

Here, 'A' is NO₂ (Nitrogen dioxide)

'B' is N₂O₄ (dinitrogen tetraoxide)

'C' is N₂O₃ (dinitrogen trioxide)

A brown gas is produced when lead nitrate (II) is heated

2Pb (NO₃)₂ 2PbO  +  4NO₂ + O₂

2NO₂ N₂O₄

2NO  + N₂O₄ 2N₂O₃ 

This is a long answer type question as classified in NCERT Exemplar

'A' is S₈ 'B' is SO₂ gas

 S₈ + 8O₂ 8SO₂

2MnO₄ ^– + 5SO₂ + 2H₂O → 5 SO₄^2– + 4H⁺ + 2Mn²⁺

(violet)                                                              (colourless)

2Fe³⁺ + SO₂ + 2H₂O → 2Fe²⁺ + SO₄^2– + 4H⁺

The de Broglie wavelength  depends on:
Planck's constant h (a universal constant),
velocity v of the particle
mass m of the particle.

Photons do not have enough energy ( )to overcome the work function (? ) of the material below the threshold frequency.The energy per photon remains too low to liberate electrons even if the light intensity is increased, so photoelectric emission cannot occur.