• Mahesmati was an ancient kingdom located in the central India in the present day. It is located in the present India Madhya Pradesh, on the banks of River Narmada.
• As per the ancient text, it was ruled by the legendry Haihaya ruler Kartavirya Arjuna. Maheshmati was the most important city in the southern part of the Avanti kingdom which later served as the capital of the Anupa Kingdom.
• It was located to the south of Ujjayini, and north of Pratishthana. Several cities located in Madhya Pradesh on the banks of River Narmada are claimed to be a part of ancient Mahesmati.

• The Godavari is India's second longest river after the Ganges river and drains into the third largest basin in India. Its source is in Trimbakeshwar, Nashik, Maharashtra.
• Son River is a perennial river located in central India. It originates near Amarkantak Hill in Gaurela-Pendra-Marwahi district of Chhattisgarh and finally merges with the Ganges River near Patna in Bihar.
• The Sarayu is a river that originates at a ridge south of Nanda Kot mountain in Bageshwar district in Uttarakhand, India.

• Assaka was a region of ancient India around and between the river Godavari. It was one of the sixteen mahajanapadas in the 6th century BCE. mentioned in the Buddhist text Anguttara Nikaya. Hence statement 1 is correct.
• Champa, also spelled Campa, city of ancient India, the capital of the kingdom of Anga (a region corresponding with the eastern part of present-day Bihar state). It is identified with two villages of that name on the south bank of the Ganges (Ganga) River east of Munger.  Hence statement 2 is correct.
• The Anguttara Nikaya, Mahavastu (Buddhist texts), Bhagwati Sutra (Jain texts) texts refer to 16 Mahajanapadas. Gandhara and Kamboj are mentioned in Anguttara Nikaya.. Hence statement 3 is not correct. 
  
• No mathura was not the capital of Kashi. Mathura was the capital of Shursena. Hence, statement 4 is incorrect.

1. ANGA : capital was Champa (identified with modern day Champanagara or Champapura village near Bhagalpur)
2. MAGADHA : first capital was Rajagriha-Girivraja (Rajgir) ; later capital was Pataliputra (Patna)
3. VRIJI/ VAJJI : capital was Vaisali (identified with modern Basarh in north Bihar)
4. MALLA : capital was Pava (present day Pawapuri in Bihar)
5. CHEDI : capital was Sothivatinagara/Shuktimati (located in the present day area around Jabalpur in MP)
6. KASI : capital was Varanasi (present day Benaras and its adjoining areas)
7. KOSALA : capital was Sravasti (present villages of Sahet-Mahet)
8. VATSA : capital was Kausambi (identified with Kosam village on the right bank of Yamuna)
9. MATSYA : capital was Vairatnagar (identified with modern Vairat in Rajasthan)
10. SURASENA : capital was Mathura
11. KURU : capital was Hastinapura
12. PANCHALA : there were 2 capitals ; Ahichhatra (modern Ramnagar in Bareilly district in UP) and Kampilya (modern Kampil in Farukhabad district in UP)
13. ASSAKA/ASHMAKA : capital was Govardhana (identified with modern day Bodhan in Maharashtra)
14. AVANTI : there were 2 capitals ; Mahishmati (identified with modern day Maheshwar in MP) and Ujjayini (modern day Ujjain in MP)
15. GANDHARA : capital was Takshashila (modern day Taxila)
16. KAMBOJA : capital was Rajapura (identified with modern day Rajauri in J&K).

• Mahajanapada is one of the sixteen kingdoms or oligarchic republics that existed in the ancient India from the sixth centuries BCE to fourth centuries BCE. Two of them were most probably 'ganas' ie. republics, and others had forms of monarchy. Ancient Buddhist texts like the Anguttara Nikaya. at several places, gives a list of sixteen great nations:
• The Vyākhyāprajñapti, a sutra of Jainism, gives a slightly different list of sixteen Mahajanapadas.

Viratnagar was the capital of Matsya Mahajanapada. This Mahajanapada was situated to the west of the Panchalas and south of the Kurus. It is situated around present-day Jaipur. Mahismati or Ujjaini was the capital of Avanti Mahajanapada. Taxila was the capital of Gandhara Mahajanapada.