Question

The SI unit of pressure is $N/{m^2}$. The unit is otherwise called
 A. pascal
 B. newton
 C. joule
 D. none of these

Answer 1

Hint: Units and Dimensions play key roles in physics. Various quantities have various dimensions. The main fundamental quantities are associated with dimensions of M, L, T, K and A for mass, length, time, temperature, and current respectively. Different physical quantities have various units and the SI unit of length is meter.

Complete answer:
It's known that there are various languages in this world. Same feelings are expressed in different languages using different terms. But when we measure a certain quantity of a body let it be mass or length or volume it remains constant wherever we go in this world. This observation led to scientists establishing a common units system to measure these quantities which will be acceptable and understood all over the world without any difficulties. Those units are called SI units or international systems of units. Meter is the SI unit of the length. Similarly, mass has its SI unit as kilogram and time has second as its SI unit..
Now there is another system of units. This is called the CGS system. Here mass is measured in grams and length is measured in centimeters and time is measured in seconds.
Pressure is the ratio of force acting upon area. SI Unit of force is newton and SI unit of area is meter square. So the unit of pressure will be $N/{m^2}$. This unit is otherwise called pascal.

Hence option A is the answer.

Note:
There are some quantities which have units while don't have dimensions. Few instances for such quantities include plane angle. and solid angle. Plane angle has a unit called radian but no dimensions. Similarly, solid angle has a unit of steradian but no dimension.