The most precise reading of the mass of an object among the following is

Options

A. 20 g
B. 20.0 g
C. 20.01 g
D. `20xx10^0` g

Answer

To determine the most precise reading of the mass of an object from the given options, we need to analyze the number of significant digits in each option. Here are the options provided:

1. 20 gram
2. 20.0 gram
3. 20.01 gram
4. 20 × 10^0 gram

Now, let's evaluate each option step by step:

### Step 1: Analyze Option 1 - 20 gram
- The number "20" has no decimal point.
- In this case, only the '2' is significant.
- Therefore, it has **1 significant digit**.

### Step 2: Analyze Option 2 - 20.0 gram
- The number "20.0" has a decimal point.
- All digits including the trailing zero after the decimal are significant.
- Therefore, it has **3 significant digits**.

### Step 3: Analyze Option 3 - 20.01 gram
- The number "20.01" also has a decimal point.
- All digits are significant, including the zeros between non-zero digits.
- Therefore, it has **4 significant digits**.

### Step 4: Analyze Option 4 - 20 × 10^0 gram
- The number "20" in scientific notation has no decimal point.
- Similar to Option 1, only the '2' is significant.
- Therefore, it has **1 significant digit**.

### Conclusion:
After analyzing all the options, we find that:
- Option 1 has 1 significant digit.
- Option 2 has 3 significant digits.
- Option 3 has 4 significant digits.
- Option 4 has 1 significant digit.

The option with the most significant digits is **Option 3: 20.01 gram**, which has **4 significant digits**. Thus, it is the most precise reading of mass among the given options.