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Question

What happens to solid carbon dioxide (dry ice) when the pressure is decreased to 1 atmosphere?

This question was previously asked in
SSC CHSL 2025 Tier 1 Question Paper (21-Nov-2025) (Shift 1)
The correct answer is

It sublimates directly into a gas.

Solid carbon dioxide is commonly called dry ice because it does not melt into a wet liquid under normal conditions.

At a pressure of 1 atmosphere, carbon dioxide cannot exist as a liquid; it changes directly from the solid state to the gaseous state.

This direct conversion of a solid into a gas without passing through the liquid phase is called sublimation.

Dry ice sublimates at about -78.5 degrees Celsius at 1 atmosphere, which is why it produces a smoky, fog-like effect.

Liquid carbon dioxide forms only under higher pressures (above about 5.1 atmospheres), so 'melts into a liquid' is incorrect here.

Because the substance neither stays solid nor freezes further, the correct description is direct sublimation into a gas.

Therefore, the correct answer is It sublimates directly into a gas.

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Similar Questions

  1. Which of the following is NOT a main factor affecting the rate of evaporation?

  2. The forces of attraction between the particles are maximum in _____ and minimum in _____.


Important Questions from States of Matter

  1. A liquid is heated up to a certain temperature. Which one of the following situation would correspond to the boiling of the liquid?

  2. Which one among the following oxides has the highest melting point?

  3. Equal volume of all gases, when measured at the same temperature and pressure, contain an equal number of particles. Who proposed the above law?

  4. Match List I with List II and select the correct answer using the code given below the Lists:

    List I (Noble gas)

    List II (Use)

    A. Argon

    1. In lights for advertising display

    B. Neon

    2. Airport landing lights and in light houses

    C. Krypton

    3. Light in photographer’s flash gun

    D. Xenon

    4. In tungsten filament to last

    Code:
  5. Match List-I with List-II and select the correct answer using the code given below the Lists:

    List I

    (Process)

    List II

    (Type of change)

    A. Heating of camphor

    1. Chemical

    B. Cooling of water vapor up to room temperature

    2. Evaporation

    C. Cooking an egg

    3. Condensation

    D. Formation of water vapor at room temperature.

    4. Sublimation

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