Gayatri Mantra is found in which book?

In which Vedic text the term ‘Varna’ is found referred for the first time?

Which of the following Rig-Vedic Gods is not mentioned in 'Boghazkoi' inscription?

Which one of the following is oldest Veda :

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

Which of the following Gods is referred to as 'Ritasya Gopa' in the Rigveda?