Revised Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (Part 9) (First Revision) which is identical with ISO 80000-9 : 2019 ‘Quantities and units — Part 9: Physical chemistry and molecular physics’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Basic Standards Sectional Committee and approval of the Production and General Engineering Division Council.

This standard was first published as IS 1890 (Part 8) ‘Quantities and units: Part 8 Space and Time’ in 1983 and subsequently revised in 1995. IS 1890 (Part 8) : 1995 was superseded by IS/ISO 80000 (Part 9) : 2009 which was published in 2014. This revision has been taken up to align it with the latest version of ISO 80000-9.

The major changes in this revision are as follows:

a) The table giving quantities and units has been simplified; and

b) Some definitions and remarks have been stated physically more precisely.