Question

what is standard temperature?

Answer 1

0 degrees celcius. It's the temperature used to get the "ideal" behaviour of gas, as well as many other things - the "standard" so other experiments repeated at the same temperature may yield the same results. There's also standard pressure, 1 atm (i.e. sea level, 760 mmHg).

Answer 2

In chemistry, IUPAC established standard temperature and pressure (informally abbreviated as STP) as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 100 kPa (14.504 psi, 0.986 atm),[1] An unofficial, but commonly used standard is standard ambient temperature and pressure (SATP) as a temperature of 298.15 K (25 °C, 77 °F) and an absolute pressure of 100 kPa (14.504 psi, 0.986 atm).

NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 101.325 kPa (14.696 psi, 1 atm).

International Standard Metric Conditions for natural gas and similar fluids[2] is 288.15 K and 101.325 kPa.