Question

Choose the incorrect option.

• A. Use of solidus (/) is recommended only for indicating a division of one letter unit symbol by another unit symbol. Not more than one solidus is used.
• B. A prefix is never used alone. It is always attached to a unit symbol and written or fixed before the unit symbol.
• C. The use of double prefixes is allowed when single prefix is available.
• D. The use of a combination of unit and the symbols for unit is avoided when the physical quantity is expressed by combining two or more units.

Answer 1

The correct option is C The use of double prefixes is allowed when single prefix is available.

The use of double prefixes is avoided when single prefix is available.
For example: ${10}^{-9}\text{m}=1\text{nm}\ne 1\text{m}\mu \text{m}$