'Litre' is the standard unit of capacity.

The conversion factor for kilometre to metre is 1000.
When we convert a bigger unit (km) to a smaller unit (m), we multiply.

Therefore, 1 km = $1\times 1000$ = 1000 m

$\text{Capacity of 5 cups}=2\text{litres}$

When we convert a larger unit (L) to a smaller unit (mL), we multiply the given measure by powers of 10.
$\therefore \text{Capacity of 5 cups}=2\times 1000\text{mL}(\because 1\text{litre}=1000\text{mL})$
$=2000\text{mL}$
$\Rightarrow \text{Capacity of 1 cup}=\frac{2000}{5}\text{mL}$
$=400\text{mL}$
Thus, the capacity of 1 cup equals 400 mL.

If we observe the picture, we see that the spoon is the smallest object which can hold the least quantity of liquid.

The cup has more capacity than the spoon.

The jug has more capacity than both the spoon and the cup.

The bucket can hold more liquid  compared to the spoon, the cup and the jug.

Measuring tape is used to measure the length. For example the length of a cloth. Compass shows the direction. Measuring can is used to measure the volume of a liquid.

The balance scale is an instrument used to measure the mass. It is the device for weighing and find how much the object weighs.

We know that 1 m = 100 cm 

Half a metre = 100 cm $÷$ 2 = 50 cm

We know that, 1 kg = 1000 g
We already have 300 g,
$\Rightarrow$1000 g - 300 g = 700 g

Therefore, 300 g + 700 g = 1000 g

When we convert a larger unit (m) to a smaller unit (cm), we multiply by the conversion factor.

Therefore, to convert length given in metres (m) to centimetres (cm) we have to multiply by 100.

If we observe the picture, the pencil on the scale is starting from 1 cm. Ideally, it should start from zero. So, subtract 1 cm from 6 cm.

i.e., Length of the pencil $=6cm-1cm=5cm$

      $\text{Weight of 1 dumbbell}=800\text{g}$$\Rightarrow \text{Weight of 4 dumbbells}=800\text{g}\times 4$
                                             $=3200\text{g}$

Since the options are in kilograms, we need to convert 3200 g to kg.

When we convert a smaller unit (g) to a larger unit (kg), we divide the given measure by the conversion factor.
         $1\text{kg}=1000\text{g}$
$\Rightarrow 3200\text{g}=\frac{3200}{1000}\text{kg}$
                 $=3.2\text{kg}$
Thus, the weight of 4 dumbbells is 3.2 kg.