Question

1 nanometer (1 nm) is equal to
A. ${\text{ 1}}{{\text{0}}^{ - 7}}m$
B. ${\text{ 1}}{{\text{0}}^{ - 9}}m $
C. ${\text{ 1}}{{\text{0}}^9}m $
D. ${\text{ None of these}} $

Answer 1

Hint: Nanometre is one of the units of length used to measure distances smaller than a metre. We obtain the shorter units of length by multiplying them by $10^{-3}m$ at each step. Other values in between them are not defined.

Complete Step-by-Step solution:
The unit of length refers to an internationally accepted standard unit used for measuring length. The most commonly used system is the S.I. system of units. In this system, the unit of length is metre (m). There is another system which is used for units called the M.K.S. system of units. In the M.K.S. system the unit of length is centimetre (cm). The unit metre and centimetre is related to each other as follows:
$ 1m = 100cm$ or $1cm = 10^{-2}m$
To measure shorter lengths than cm, there are other units also defined as given below. Since m is the S.I. unit, all these lengths are related to m as follows.
Millimetre:$1mm=10^{-3}m$
Micrometre: $1\mu m=10^{-6}m$
Nanometre: $1nm=10^{-9}m$
Picometre: $1pm=10^{-12}m$
Femtometre: $1fm=10^{-15}m$
Hence, the correct answer to the question is option B.
Additional Information:
Here we have reduced the length but we can also go in the other direction, that is, we can also define bigger units of length as follows:
Kilometre: $1km=10^3m$
We can go beyond this in units of million ($10^6$), billion ($10^9$) and trillion ($10^{12}$) and so on.
For very large or astronomical distances, we have units like light year, Astronomical units defined as follows:
Light year: It is the distance travelled by light in one year.
$$1ly=10^{13}km=10^{16}m$$
Astronomical unit: It is the distance between earth and sun.
$$1AU=149.6 \times 10^6 km=149.6 \times 10^9 m$$

Note: We may go beyond femtometre also but with present scientific technology, length smaller than $10^{-15}m$ has not been observed or measured yet. All the lengths between these units are not officially named, instead they are expressed in terms of given units.