Which is the best instrument for testing the state of charge of car battery?

Options

A. Voltmeter
B. Ammeter
C. Voltameter
D. Hydrometer

Explanation

To determine the best instrument for testing the state of charge of a car battery, we can analyze the options provided: Voltmeter, Ammeter, Voltameter, and Hydrometer.

### Step-by-Step Solution:

1. **Understanding the Options**:
- **Voltmeter**: Measures the voltage across the battery terminals. While it can provide some information about the battery's charge, it does not give a complete picture of the state of charge.
- **Ammeter**: Measures the current flowing in the circuit. It does not indicate the charge level of the battery directly.
- **Voltameter**: Used to measure the quantity of electricity passed through a solution, but not specifically for battery charge.
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