Total number of molecules which can form H-bond among themselves.
`SiH_(3)OH, HCN, B(OMe)_(3), NHMe_(2), CH_(2)CONH_(2), HCHO, HCOOH, NH_(2)OH, H_(4)SiO_(4)`

Explanation

To determine the total number of molecules from the given list that can form hydrogen bonds among themselves, we will analyze each molecule based on its structure and the presence of hydrogen bonding functional groups (such as -OH, -NH, or -HF).

### Step-by-Step Solution:

1. **Identify the molecules:**
The molecules provided are:
- SiH₃OH
- HCN
- B(OMe)₃
- NHMe₂
- CH₂CONH₂
- HCHO
- HCOOH
- NH₂OH
- H₄SiO₄

2. **Analyze each molecule for hydrogen bonding:**
- **SiH₃OH**: Contains -OH group. Can form hydrogen bonds. **(Yes)**
- **HCN**: Contains -NH group. Can form hydrogen bonds. **(Yes)**
- **B(OMe)₃**: The -O is bonded to methyl groups (OMe), which does not allow for hydrogen bonding. **(No)**
- **NHMe₂**: Contains -NH group. Can form hydrogen bonds. **(Yes)**
- **CH₂CONH₂**: Contains -NH₂ group. Can form hydrogen bonds. **(Yes)**
- **HCHO**: Contains -OH (aldehyde). However, the carbonyl oxygen is double-bonded and does not participate in hydrogen bonding. **(No)**
- **HCOOH**: Contains -COOH (carboxylic acid). Can form hydrogen bonds. **(Yes)**
- **NH₂OH**: Contains -OH group. Can form hydrogen bonds. **(Yes)**
- **H₄SiO₄**: Contains -OH groups. Can form hydrogen bonds. **(Yes)**

3. **Count the molecules that can form hydrogen bonds:**
- SiH₃OH: Yes
- HCN: Yes
- B(OMe)₃: No
- NHMe₂: Yes
- CH₂CONH₂: Yes
- HCHO: No
- HCOOH: Yes
- NH₂OH: Yes
- H₄SiO₄: Yes

From the analysis, the molecules that can form hydrogen bonds are:
- SiH₃OH
- HCN
- NHMe₂
- CH₂CONH₂
- HCOOH
- NH₂OH
- H₄SiO₄

This gives us a total of **7 molecules** that can form hydrogen bonds.

### Final Answer:
The total number of molecules that can form hydrogen bonds among themselves is **7**.