Behaviour of an RC Beam in Flexure

1. What is the allowable design stress of concrete in structures at the Ultimate limit state as per IS-456?
2. What is the allowable design yield stress of steel at the Ultimate limit state as per IS-456?
3. Which type of RC beam section experiences a brittle, sudden failure?
4. In limit state method, xu > xu,max represents which type of beam section?
5. The moment at which the first crack appears on the beam is known as?