The decreasing order of polarity of the bonds in `NH_3, PH_3, AsH_3 and SbH_3` is in the order

Options

A. `NH_3 gt PH_3 gt AsH_3 gt SbH_3`
B. `SbH_3 gt AsH_3 gt PH_3 gt NH_3`
C. `NH_3gt AsH_3 gt PH_3 gtSbH_3`
D. `NH_3 gt SbH_3 gt AsH_3 gt PH_3`

Explanation

To determine the decreasing order of polarity of the bonds in NH3, PH3, AsH3, and SbH3, we need to analyze the polarizing power of the central atom in each hydride. The polarity of the bonds is influenced by the size of the central atom, which affects its ability to attract the bonding electrons.

### Step-by-Step Solution:

1. **Identify the Central Atoms**: The central atoms in the given hydrides are nitrogen (N) in NH3, phosphorus (P) in PH3, arsenic (As) in AsH3, and antimony (Sb) in SbH3.

2. **Understand Polarizing Power**: The polarizing power of an atom is its ability to distort the electron cloud of the bonded atom (in this case, hydrogen). A smaller atom has a higher charge density and can polarize the electron cloud more effectively.

3. **Size of the Atoms**: The size of the central atoms increases as we move down the group in the periodic table:
- Nitrogen (N) < Phosphorus (P) < Arsenic (As) < Antimony (Sb)

4. **Relate Size to Polarizing Power**: As the size of the central atom increases, its polarizing power decreases:
- N (smallest) > P > As > Sb (largest)

5. **Determine the Order of Polarity**: Since smaller atoms have higher polarizing power, the order of polarity of the bonds in these hydrides will be:
- NH3 (most polar) > PH3 > AsH3 > SbH3 (least polar)

6. **Final Answer**: Therefore, the decreasing order of polarity of the bonds in NH3, PH3, AsH3, and SbH3 is:
- NH3 > PH3 > AsH3 > SbH3