perimentProcedureObservationIWhite powder is added to water.Gas is given off.IIA solution is heated until it boils.Vapour rises, and solute is left in the beaker.IIIYellow powder is added to water.Yellow powder is added to water.IVA pure solution is added to another pure solution.A powder appears at the bottom of the beaker.In which two of the experiments did a physical change occur?

To determine in which two of the experiments a physical change occurred, let's analyze each experiment step by step:

Experiment I

Procedure: White powder is added to water. Observation: Gas is given off.

• Analysis: The production of gas suggests a chemical reaction is taking place. This is likely a chemical change.

Experiment II

Procedure: A solution is heated until it boils. Observation: Vapour rises, and solute is left in the beaker.

• Analysis: Boiling is a physical process where a liquid changes to gas. The solute left behind indicates a physical separation process (evaporation). This is a physical change.

Experiment III

Procedure: Yellow powder is added to water. Observation: Yellow powder is added to water.

• Analysis: There is no indication of a chemical reaction (no gas, color change, or precipitate formation). The yellow powder simply disperses in water, which is a physical change.

Experiment IV

Procedure: A pure solution is added to another pure solution. Observation: A powder appears at the bottom of the beaker.

• Analysis: The formation of a powder (precipitate) suggests a chemical reaction between the two solutions. This is a chemical change.

Conclusion

The two experiments in which a physical change occurred are:

• Experiment II: Boiling the solution and leaving the solute behind.
• Experiment III: Adding yellow powder to water without any chemical reaction.

So, the physical changes occurred in Experiment II and Experiment III.

Para determinar en cuáles de los experimentos ocurrió un cambio físico, debemos analizar cada uno de los procedimientos y observaciones:

I. Se añade un polvo blanco al agua y se desprende gas.

• Esto sugiere una reacción química, ya que se produce un gas.

II. Se calienta una solución hasta que hierve. El vapor sube y el soluto queda en el vaso.

• Este es un cambio físico, ya que solo se está separando el soluto del solvente mediante un cambio de estado (evaporación).

III. Se añade un polvo amarillo al agua. Se añade un polvo amarillo al agua.

• No se menciona ninguna reacción o cambio, por lo que parece que el polvo simplemente no se disuelve. Esto es un cambio físico.

IV. Se añade una solución pura a otra solución pura. Aparece un polvo en el fondo del vaso.

• Esto sugiere una reacción química, ya que se forma un precipitado.

Por lo tanto, los experimentos en los que ocurrió un cambio físico son el II y el III.