The correct relation for speed is:

1. Speed = distance x time

2. Speed = $\dfrac{\text{distance}}{\text{time}}$

3. Speed = $\dfrac{\text{time}}{\text{distance}}$

4. Speed = $\dfrac{\text{1}}{\text{distance x time}}$

A boy travels a distance 150 m in 1 minute. His speed is:

1. 150 m s^-1
2. 2.5 m s^-1
3. 25 m s^-1
4. 9 m s^-1

Assertion (A): The density of water decreases when it is cooled from 4 °C to 0 °C.

Reason (R): Volume of water increases in cooling from 4 °C to 0 °C.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true and R is not the correct explanation of A
3. Assertion is false but reason is true
4. Assertion is true but reason is false

Fill in the blanks:

(a) 1 m³ = …………… cm³.

(b) The volume of an irregular solid is determined by the method of …………… .

(c) Volume of a cube = …………… .

(d) The area of an irregular lamina is measured by using a …………… .

(e) Equal masses of different substances have different …………… .

(f) The S.I. unit of density is …………… .

(g) 1 g cm^-3 = …………… kg m^-3.

(h) 36 km h^-1 = …………… m s ^-1.

(i) Speed of a vehicle at a particular instant is shown by …………… .