How can the salt return? — questions

1. Suggest / Explain

A and B form a dry mixture. Neither reacts with the candidate liquids; paper retains undissolved B. Water dissolves only A. J dissolves both. Choose a liquid for dissolving and filtering, then explain your choice.

Circle one answer.

• Water
• J
• Both work equally well
• Neither can work

Explain what happens to A and B with your choice, and why J fails to split them.

Nudge (only if you are stuck): Which liquid gives the components different behaviour instead of keeping them together?

2. Explain

T dissolves neither C nor D. U dissolves both. Paper retains any undissolved grains. After stirring and filtering, describe where C and D would be with each candidate. Explain whether either liquid separates them.

Write the number of the matching option.

1. Together in the residue
2. Together in the filtrate
3. C in residue; D in filtrate
4. D in residue; C in filtrate

• With solvent T: ______
• With solvent U: ______

Explain why neither candidate achieves separation of C from D.

Nudge (only if you are stuck): Do both components enter the same product or different ones?

3. Suggest / Explain / Describe

You want to separate E and F by dissolving and filtering. Both candidate liquids are teacher-approved and react with neither solid. R dissolves E only; S dissolves both. Paper retains undissolved F. Choose a liquid and describe residue and filtrate. Don't propose solvent recovery.

Circle one answer.

• R
• S
• Either R or S
• Neither R nor S

Justify your choice and describe both residue and filtrate. Recovery from the filtrate is not requested.

Nudge (only if you are stuck): Which candidate keeps F solid while E dissolves? Must the useful solvent be called water?

4. Explain

A note says V dissolves G. Nothing is said about H, which is mixed with G. A pupil claims V must separate them by dissolving and filtering. Explain whether the evidence is sufficient. Identify the missing property.

Nudge (only if you are stuck): Could V dissolve H as well? What must remain separate for the filter to help?

5. Describe / Explain

Only salt solution enters an open basin. Water is removed without losing or chemically changing sodium chloride. Describe the solid left and where the water goes. Explain why heating hasn't made new salt.

Nudge (only if you are stuck): Which substances were already there? Which crossed the basin's boundary?

6. Explain

P is dissolved in water. The given data say P decomposes if heated to dryness by the proposed method. You want unchanged P. Choose the justified decision and explain it.

Circle one answer.

• Heat to dryness because every solute behaves like salt.
• Use the same filter to catch dissolved P.
• Reject this heating procedure; a different validated method is needed.
• Assume the decomposition data do not matter.

Explain how the supplied property affects recovery of unchanged P.

Nudge (only if you are stuck): Would any solid residue count as unchanged P, even if the data say P decomposes?

7. Explain

A pupil wants both salt and liquid water from salt solution. They propose an open evaporating basin with no vapour collection. Explain which product it can collect under this model and why the full goal fails.

Nudge (only if you are stuck): Is water leaving the basin the same as water being collected in another vessel?

8. Explain

An open basin and its contents lose measured mass as water evaporates from salt solution. A pupil says matter therefore isn't conserved. Explain how the measurement and conservation can both be consistent. No calculation is needed.

Nudge (only if you are stuck): Where is the water after it leaves? Does the measured boundary still include it?