Which of the following statement is wrong?

The \(Cl-C-Cl\) bond angle is the same in both \(CCl_4\) and \(CH_2Cl_2\).

The correct answer is option 3. The \(Cl-C-Cl\) bond angle is the same in both \(CCl_4\) and \(CH_2Cl_2\).

Let us analyze each statement to identify which one is incorrect:

1. Vital force theory of the origin of organic compounds was discarded by Wohler’s synthesis of urea from ammonium cyanate.

The vital force theory posited that organic compounds could only be synthesized by living organisms through a "vital force." This theory was discarded when Friedrich Wöhler synthesized urea, an organic compound, from ammonium cyanate, an inorganic compound, in 1828. This demonstrated that organic compounds could be created from inorganic substances, refuting the vital force theory. Thus the statement is correct.

2. Tetrahedral nature of carbon was proposed by Vant Hoff and Label.

The tetrahedral geometry of carbon atoms in organic compounds was indeed proposed by Jacobus Henricus van 't Hoff and Joseph Achille Le Bel independently in 1874. This theory explained the three-dimensional arrangement of atoms around a carbon atom with four single bonds. Thus the statement is correct.

3. The ClCCl bond angle is the same in both \(CCl_4\) and \(CH_2Cl_2\).

In \(CCl_4\), the molecule is tetrahedral, with bond angles of approximately 109.5° between the Cl-C-Cl atoms. However, in \(CH_2Cl_2\) (dichloromethane), the presence of hydrogen atoms affects the bond angles. The Cl-C-Cl bond angle in \(CH_2Cl_2\) is not exactly the same as in \(CCl_4\) due to the different repulsions between hydrogen and chlorine atoms. Thus the statement is correct.

4. Bond angle in ethylene and benzene is the same.

In ethylene (\(C_2H_4\)), the carbon atoms are sp^2 hybridized, leading to bond angles of approximately 120° around the double bond. In benzene (\(C_6H_6\)), each carbon is also sp^2 hybridized, leading to bond angles of 120° throughout the ring. Thus, the bond angles in ethylene and benzene are indeed the same. Thus the statement is correct.

Conclusion: The incorrect statement is: 3. The ClCCl bond angle is the same in both \(CCl_4\) and \(CH_2Cl_2\).

In \(CH_2Cl_2\), the bond angles differ from those in \(CCl_4\) due to the presence of hydrogen atoms. The bond angle in \(CCl_4\) is 109.5°, while in \(CH_2Cl_2\) it is less due to the different spatial arrangement and repulsions between hydrogen and chlorine atoms.