Which of the followig is false?

Options

A. Saline water slows down rusting
B. In daniell cel, if concentrations of the solutions are doubled, the emf of the cell is also doubled.
C. EMF of a cell is an intensive whereas free energy change, `DeltaG` is extensive.
D. Galvanised iro sheets remain protected from rusting even if a crack is developed.

Explanation

To determine which of the statements is false, we will analyze each option one by one.

### Step 1: Analyze Option 1
**Statement:** Saline water slows down rusting.

- **Explanation:** Saline water (salt water) does not prevent rusting; instead, it can accelerate the rusting process once it has started. While salt water may not cause rusting directly, it can enhance the corrosion of metals that are already rusting due to the presence of electrolytes that facilitate electron transfer. Therefore, this statement is **false**.

### Step 2: Analyze Option 2
**Statement:** In a Daniell cell, if the concentration of the solution is doubled, the EMF of the cell also doubles.

- **Explanation:** The EMF (Electromotive Force) of a Daniell cell is given by the Nernst equation:
\[ E_{cell} = E^0_{cell} - \frac{0.0591}{n} \log \left(\frac{[products]}{[reactants]}\right) \]
Doubling the concentration of the reactants or products does not simply double the EMF; the relationship is logarithmic. Therefore, this statement is also **false**.

### Step 3: Analyze Option 3
**Statement:** EMF of a cell is an intensive property whereas free energy change (ΔG) is an extensive property.

- **Explanation:** This statement is true. EMF is an intensive property, meaning it does not depend on the amount of substance present. In contrast, ΔG is an extensive property, which depends on the amount of substance. Therefore, this statement is **true**.

### Step 4: Analyze Option 4
**Statement:** A galvanized iron sheet remains protected from rusting even if a crack is developed.

- **Explanation:** Galvanization involves coating iron with a layer of zinc or aluminum to prevent rusting. If a crack develops in the galvanized layer, the exposed iron can rust. While the galvanized coating provides protection, it is not foolproof if the coating is compromised. Thus, this statement is also **false**.

### Conclusion
The false statements are:
1. Saline water slows down rusting.
2. In a Daniell cell, if the concentration of the solution is doubled, the EMF of the cell also doubles.
4. A galvanized iron sheet remains protected from rusting even if a crack is developed.

The correct answer is that **Option 1 and Option 2 are false statements**.