Diffusion selectivity in dialysis tubing

Steps:

• Iodine test remains orange-brown, indicating starch stays inside tubing as it cannot pass through pores.
• Benedict's test changes from blue to red over time, showing glucose (reducing sugar) diffuses out into water.
• No evidence of water movement, such as volume change in tubing, to support osmosis into it.
• Thus, statements 1 and 2 are supported, but 3 lacks direct observation.

Why B is correct:

• Benedict's test detects reducing sugars like glucose; color progression confirms diffusion down concentration gradient per Fick's law.

Why the others are wrong:

• A includes unsupported water diffusion.
• C omits confirmed glucose diffusion.
• D excludes valid starch retention by pores.

Final answer: B