Question

Radhika and Shivangi took two glass plates and two lighted candles. Radhika held the glass plate inside the flame of the candle and Shivangi held it slightly above the candle flame. Which of the following statements is correct?

• A. Shivangi's glass plate will have blackish unburnt carbon particles deposition but Radhika's glass plate will not
• B. Both Shivangi's and Radhika's glass plates will have blackish deposition of unburnt carbon particles.
• C. Neither Shivangi's nor Radhika's glass plate will have blackish deposition of unburnt carbon particles.
• D. Radhika's glass plate will have blackish unburnt carbon particles deposition but Shivangi's glass plate will not.

Answer 1

The correct option is D Radhika's glass plate will have blackish unburnt carbon particles deposition but Shivangi's glass plate will not.

$\bullet$ Radhika held the glass plate inside the flame. Therefore, she held the plate in the luminous zone. This zone is the zone of incomplete combustion. Therefore, a circular blackish ring of unburnt carbon particles will be obtained on her glass plate.
$\bullet$ Shivangi held the glass plate slightly above the flame i.e., in the non-luminous zone. As this zone is the zone of complete combustion, no unburnt carbon particle deposition will take place in this case.