Question

Which of the following is the non-metric unit of length?
A) Millimeters
B) Centimeters
C) Meters
D) Inches

Answer 1

A metric system is a system of measurement that succeeded in the decimalized system based on the meter. Therefore all the units of length which are represented in the terms of meters by adding a prefix are all metric units whereas all the rest units are the non-metric units of length.

Complete step by step answer:
A system of measurement that succeeded in the decimalized system based on the meter is called a metric system. Since in all the first three systems we have the units which are decimalized units based on the meter. Hence the millimeters, centimeters, and meters are all the metric units of length whereas the inches are a non-metric unit of length.

Therefore the correct option is D.

Additional information:
Units are of two types:
(i) Fundamental units
(ii) Derived units
System of units: A complete set of units that are used to measure all kinds of fundamental and derived quantities is called a system of units.
Some of the commonly used systems of units are as follows -
1. C.G.S system:- This is also known as the Gaussian system of units that uses centimeter ($cm$), gram ($g$), second ($s$) as the fundamental units of length mass, time respectively.
2. F.P.S system:- It is the British Engineering system of units which uses foot ($ft$), pound ($Ib$), and second ($s$) as the fundamental units of length, mass and time respectively
3. M.K.S system:- In this system, the units of length, mass and time are meter ($m$), kilogram ($kg$), and second ($s$) respectively.

Note:
Also, remember the units conversion of various units of length in terms of meter which given as below:
$1mm = {10^{ - 3}}m \\\ 1cm = {10^{ - 2}}m \\\ 1inch = 0.0254m \\\$