**Polar and Nonpolar Molecules**

In order to determine whether a molecule is polar or nonpolar, we need to consider the molecule's geometry and the polarity of its bonds. A polar molecule is one in which the electron distribution is not symmetrical, resulting in a partial positive charge on one end and a partial negative charge on the other end. On the other hand, a nonpolar molecule has symmetrical electron distribution, resulting in no partial charges.

**a) CS2 - Carbon Disulfide**

- Carbon disulfide (CS2) consists of one carbon atom bonded to two sulfur atoms.
- The carbon-sulfur bonds are polar due to the difference in electronegativity between carbon (2.55) and sulfur (2.58).
- However, since the molecule's geometry is linear, the polar bonds cancel each other out, resulting in a nonpolar molecule.
- Therefore, CS2 is a nonpolar molecule.

**b) BF3 - Boron Trifluoride**

- Boron trifluoride (BF3) consists of one boron atom bonded to three fluorine atoms.
- The boron-fluorine bonds are polar due to the difference in electronegativity between boron (2.04) and fluorine (3.98).
- However, the molecule's geometry is trigonal planar, with the fluorine atoms arranged symmetrically around the boron atom.
- As a result, the polar bonds cancel each other out, and BF3 is a nonpolar molecule.

**c) SnCl2 - Tin(II) Chloride**

- Tin(II) chloride (SnCl2) consists of one tin atom bonded to two chlorine atoms.
- The tin-chlorine bonds are polar due to the difference in electronegativity between tin (1.96) and chlorine (3.16).
- The molecule's geometry is bent or V-shaped, with the two chlorine atoms on one side and the tin atom on the other.
- Since the molecule is not symmetrical, the polar bonds do not cancel each other out, resulting in a polar molecule.
- Therefore, SnCl2 is a polar molecule.

**d) PbCl4 - Lead(IV) Chloride**

- Lead(IV) chloride (PbCl4) consists of one lead atom bonded to four chlorine atoms.
- The lead-chlorine bonds are polar due to the difference in electronegativity between lead (2.33) and chlorine (3.16).
- The molecule's geometry is tetrahedral, with the four chlorine atoms arranged symmetrically around the lead atom.
- Due to the symmetrical arrangement, the polar bonds cancel each other out, resulting in a nonpolar molecule.
- Therefore, PbCl4 is a nonpolar molecule.

In summary, CS2 and BF3 are nonpolar molecules, while SnCl2 is a polar molecule. PbCl4 is also a nonpolar molecule.

Ans 3).... SnCl2 Sn has 4 electrone in outer most orbital,2 electrone including in bonding with 2 ClNd another 2 electrone make the part of lone pair Which is shown polarity