The possible oxidation number of As are :

Explanation

To determine the possible oxidation numbers of arsenic (As), we will follow these steps:

### Step 1: Identify the electronic configuration of arsenic.
Arsenic has an atomic number of 33. Its electronic configuration is:
\[ \text{Arsenic: } [Ar] 3d^{10} 4s^2 4p^3 \]

### Step 2: Determine the number of valence electrons.
The valence shell for arsenic is the fourth shell (n=4), which contains:
- 2 electrons in the 4s subshell
- 3 electrons in the 4p subshell

Thus, the total number of valence electrons is:
\[ 2 \text{ (from 4s)} + 3 \text{ (from 4p)} = 5 \text{ valence electrons} \]

### Step 3: Calculate the maximum oxidation number.
The maximum oxidation number corresponds to the total number of valence electrons that arsenic can lose. Since arsenic can lose all 5 valence electrons, the maximum oxidation number is:
\[ +5 \]

### Step 4: Calculate the minimum oxidation number.
The minimum oxidation number corresponds to the number of electrons arsenic needs to gain to complete its octet. The p subshell can hold a maximum of 6 electrons, and arsenic currently has 3. Therefore, it needs to gain:
\[ 6 - 3 = 3 \text{ electrons} \]
Thus, the minimum oxidation number is:
\[ -3 \]

### Step 5: List all possible oxidation numbers.
The possible oxidation numbers of arsenic will range from the minimum oxidation number to the maximum oxidation number, inclusive. Therefore, the possible oxidation numbers are:
\[ -3, -2, -1, 0, +1, +2, +3, +4, +5 \]

### Conclusion:
The possible oxidation numbers of arsenic are:
\[ -3, -2, -1, 0, +1, +2, +3, +4, +5 \]