Question: What's the NO of the standard with HC of 1.23 g/kWh?
Schema: create table table_2780146_6 (no_x__g_kwh_ varchar, hc__g_kwh_ varchar, PRIMARY KEY (no_x__g_kwh_))
SQL: select no_x__g_kwh_ from table_2780146_6 where hc__g_kwh_ = "1.23"