the device used for measuring the mass of atoms and molecules is

Options

A. spring balance
B. torsional balance
C. mass specrograph
D. common balance

Explanation

To solve the question regarding the device used for measuring the mass of atoms and molecules, we can follow these steps:

### Step 1: Identify the Question
The question asks for the specific device that measures the mass of atoms and molecules.

### Step 2: Analyze the Options
We have four options to consider:
1. Spring balance
2. Torsional balance
3. Mass spectrograph
4. Common balance

### Step 3: Evaluate Each Option
- **Spring Balance**: This device measures weight based on the spring's extension but is not specifically designed for atomic or molecular mass measurement.
- **Torsional Balance**: This device is used to measure gravitational acceleration and is not suitable for measuring atomic or molecular mass.
- **Mass Spectrograph**: This device is specifically designed to measure the mass of atoms and molecules by analyzing the mass-to-charge ratio of ions.
- **Common Balance**: This is a general balance used for measuring mass but not specifically for atoms and molecules.

### Step 4: Conclusion
After evaluating all the options, the device that is specifically used for measuring the mass of atoms and molecules is the **Mass Spectrograph**.

### Final Answer
The device used for measuring the mass of atoms and molecules is the **Mass Spectrograph**.

---