Find the factors of 48. Convert 3.75 kg to grams, 5 L to milliliters, 10000 m to kilometers, and 400 cm to meters.

$3.75 \text{ kg} = 3.75 \times 1000 \text{ g} = 3750 \text{ g}$  
So, پونے چار کلو گرام = $\boxed{\text{3750}}$ گرام

2. 5 لیٹر (5 Liters) to milliliters

$5 \text{ L} = 5 \times 1000 \text{ mL} = 5000 \text{ mL}$  
So, 5 لیٹر = $\boxed{\text{5000}}$ ملی لیٹر

3. 10000 میٹر (10000 Meters) to kilometers

$10000 \text{ m} = \frac{10000}{1000} \text{ km} = 10 \text{ km}$  
So, 10000 میٹر = $\boxed{\text{10}}$ کلومیٹر

4. 400 سینٹی میٹر (400 Centimeters) to meters

Total length of wire = $4 \text{ meters } 40 \text{ cm}$
Since $1 \text{ meter} = 100 \text{ cm}$,
$4 \text{ meters} = 4 \times 100 \text{ cm} = 400 \text{ cm}$
Total length = $400 \text{ cm} + 40 \text{ cm} = 440 \text{ cm}$

Length of each piece = $5 \text{ cm}$
Number of pieces = $\frac{\text{Total length}}{\text{Length of each piece}} = \frac{440 \text{ cm}}{5 \text{ cm}}$
Number of pieces = 88
From this wire, $\boxed{\text{88}}$ pieces will be prepared.