I was attempting this numerical from my textbook:

"A definite mass of an ideal gas at NTP is allowed to expand to four times its original volume i) slowly, ii) suddenly. Calculate its final temperature and pressure in each case."

The author has taken the Temperature (T1) at NTP as 0°C, and Pressure at NTP as 76 cm of Hg. But isn't the Temperature at NTP 20°C (293 K)? I would like to know the correct value of Temperature at NTP.