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This question is about the physics of evaporation and latent heat. Option A (Cap prevents air from entering) is partially correct in the sense that the cap does seal the pen, but the scientific explanation given in the image is more specifically about latent heat of evaporation. While preventing air contact does reduce evaporation, the key concept tested is latent heat. Option B (Cap maintains high pressure) is incorrect — the cap does not significantly increase internal pressure. The pen is not an airtight pressure vessel. Pressure effects play a negligible role in keeping pen ink from drying compared to the latent heat mechanism. Option C (Ink absorbs latent heat from surroundings to evaporate, prevented by cap) is CORRECT — the image states: पेन का टुकड़ा ठंडा नहीं होने देता, क्योंकि — क्योंकि पेन से गुप्त ऊष्मा प्राप्त कर बर्फ पिघलने लगती है तथा ऊष्मा का हास होने से पेन ठंडा हो जाता है. For evaporation to occur, ink needs to absorb latent heat of vaporization from its surroundings. When the cap is on, the air space inside is quickly saturated with vapor, stopping further evaporation. The cap essentially prevents the heat transfer mechanism needed for evaporation. Option D (Cap keeps pen warm) is incorrect — the cap is not a heater. Keeping the pen warm would actually increase evaporation, not prevent it. The explanation involves latent heat absorption, not warmth.
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Heat is a form of energy that transfers between objects or systems due to a temperature difference, moving from a hotter body to a cooler one until thermal equilibrium is reached.
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