Explanation:

The Rig Vedic period refers to the period in ancient Indian history when the Rig Veda, the oldest of the four Vedas, was composed. This period is estimated to be between 1500 BCE and 1200 BCE. During this time, certain social practices were prevalent, while others were not yet in existence.

During the Rig Vedic period, the following practices were not in existence:

1. Dowry: Dowry is the practice of giving gifts or money to the groom or his family by the bride's family at the time of marriage. This practice was not prevalent during the Rig Vedic period. Instead, the bride's family would give a gift called "kanyadaan" to the groom, which symbolized the giving away of the daughter.

2. Child-marriage: Child-marriage refers to the practice of marrying off children, usually girls, at a young age. During the Rig Vedic period, child-marriage was not practiced. Marriage was generally solemnized when both the bride and groom had attained a suitable age and were capable of fulfilling their marital responsibilities.

On the other hand, the following practices were prevalent during the Rig Vedic period:

1. Divorce: Divorce was allowed during the Rig Vedic period. If a husband and wife were unable to live harmoniously, they could separate by mutual consent. Divorce was considered a social stigma, but it was an accepted practice.

2. Widow-marriage: Widow-marriage, which refers to the remarriage of widows, was also practiced during the Rig Vedic period. If a woman became a widow, she could remarry and lead a normal married life. This practice was aimed at providing social and economic security to widowed women.

In conclusion, during the Rig Vedic period, the practices of dowry and child-marriage were not prevalent, while divorce and widow-marriage were accepted social practices.