Capital gain in case of Acquisition by a US Listed company of an Indian unlisted co.

An unlisted Indian company in existence since March 2018 is getting acquired by a NASDAQ-listed company and the sale consideration is shares in the NASDAQ-listed US company against shares in Indian acquiree company 

Need to understand as to the "When does taxability of capital gain arise" under the following scenarios: 

1. Shares are issued by the NASDAQ-listed US company to the existing shareholders of the acquiree—without a lock-in period. The  shareholders of the acquiree hold the shares and do not intend to sell them. What is the capital gain and when is it taxable? 

2. Shares are issued by the NASDAQ-listed US company to the existing shareholders of the acquiree—without a lock-in period. The  shareholders of the acquiree sell the shares. What is the capital gain and when is it taxable? 

3. Shares are issued by the NASDAQ-listed US company to the existing shareholders of the acquiree with a lock-in period of 12 months. The shareholders of the acquiree do not intend to sell the shares. What is the capital gain and when is it taxable? 
4. Shares are issued by the NASDAQ-listed US company to the existing shareholders of the acquiree with a lock-in period of 12 months. The shareholders of the acquiree sell the shares after the lock-in period. What is the capital gain and when is it taxable?