Which Mandala of Rig Veda is completely dedicated to ‘Soma’?

The ninth mandala of the Rig Veda is devoted wholly to:

Which of the following is a characteristic of Mandala IX of the Rigveda?

The compilation of which among the following is based upon the Rig Veda?

Give the name of the tribe which is not related to the ‘Panchjana’ of the Rig Veda Aryans:

Which one of the following is not related to the Rigvedic period?