The operating temperature range for the Haber process is $350-500^{\circ}C$. It is used for the production of ammonia at

1. $20 \:MPa$ using $Fe$ catalyst in an exothermic reaction
2. $0.1 \:MPa$ using $Fe$ catalyst in an exothermic reaction
3. $20 \:MPa$ using $Fe$ catalyst in an endothermic reaction
4. $20 \:MPa$ using zeolite catalyst in an endothermic reaction