A certain household has consumed 250 units of energy during a month. How much energy is this in joules ?

Options

A. ` 9 xx10^8 J`
B. `9 xx10^6 J`
C. `0.9 xx10^6 J`
D. `0.9 xx10^8 J`

Explanation

To convert the energy consumed by the household from units to joules, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Units**: The household has consumed 250 units of energy. In electrical terms, 1 unit is equivalent to 1 kilowatt-hour (kWh). Therefore, 250 units = 250 kWh.

2. **Convert Kilowatt-Hours to Joules**: We know that:
- 1 kilowatt (kW) = 1000 watts (W)
- 1 hour = 3600 seconds

Therefore, we can convert kilowatt-hours to joules using the formula:
\[ \text{Energy (in joules)} = \text{Energy (in kWh)} \times 1000 \, \text{W/kW} \times 3600 \, \text{s/h} \]

3. **Substitute the Values**:
\[ \text{Energy (in joules)} = 250 \, \text{kWh} \times 1000 \, \text{W/kW} \times 3600 \, \text{s/h} \]

4. **Calculate**:
\[ = 250 \times 1000 \times 3600 \]
\[ = 250 \times 3,600,000 \]
\[ = 900,000,000 \, \text{J} \]

5. **Express in Scientific Notation**:
\[ 900,000,000 \, \text{J} = 9 \times 10^8 \, \text{J} \]

### Final Answer:
The energy consumed by the household is \( 9 \times 10^8 \) joules.

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