**Polar and Nonpolar Bonds**

A bond is considered polar if there is a significant difference in electronegativity between the atoms involved, leading to an uneven distribution of electron density. On the other hand, a bond is nonpolar if the electronegativity difference between the atoms is negligible or nonexistent, resulting in an even distribution of electron density.

Let's analyze each compound to determine which ones contain polar and nonpolar bonds:

**1) H2O2 (Hydrogen Peroxide):**
Hydrogen peroxide consists of two hydrogen atoms and two oxygen atoms. The electronegativity of hydrogen is 2.2, while oxygen has an electronegativity of 3.44. Since there is a significant difference in electronegativity between hydrogen and oxygen, the O-H bonds in hydrogen peroxide are polar. Additionally, the O-O bond is also polar. Hence, H2O2 contains polar bonds.

**2) CH4 (Methane):**
Methane is composed of one carbon atom and four hydrogen atoms. Carbon has an electronegativity of 2.55, while hydrogen's electronegativity is 2.2. The electronegativity difference between carbon and hydrogen is relatively small, making the C-H bonds in methane nonpolar. Therefore, CH4 contains nonpolar bonds.

**3) HCN (Hydrogen Cyanide):**
Hydrogen cyanide consists of one hydrogen atom, one carbon atom, and one nitrogen atom. Hydrogen has an electronegativity of 2.2, carbon has an electronegativity of 2.55, and nitrogen has an electronegativity of 3.04. The electronegativity difference between hydrogen and carbon is negligible, resulting in a nonpolar C-H bond. However, the electronegativity difference between carbon and nitrogen is significant, indicating a polar C-N bond. Thus, HCN contains both polar and nonpolar bonds.

**4) NH4Cl (Ammonium Chloride):**
Ammonium chloride consists of one nitrogen atom, four hydrogen atoms, and one chlorine atom. Nitrogen has an electronegativity of 3.04, hydrogen has an electronegativity of 2.2, and chlorine has an electronegativity of 3.16. The electronegativity difference between nitrogen and hydrogen is significant, resulting in polar N-H bonds. Moreover, the electronegativity difference between nitrogen and chlorine is also significant, leading to a polar N-Cl bond. Therefore, NH4Cl contains both polar and nonpolar bonds.

In summary, out of the given compounds, H2O2, HCN, and NH4Cl contain both polar and nonpolar bonds, while CH4 only contains nonpolar bonds. The determination of polar or nonpolar bonds is based on the electronegativity difference between the atoms involved.

H2O2
It contains two OH bonds and one O-O bond where the O-O bond is non-polar and OH bond is polar