Section 5 of The Hindu Marriage Act

5. Conditions for a Hindu marriage.— A marriage may be solemnized between any two Hindus, if the following conditions are fulfilled, namely:—

(i) neither party has a spouse living at the time of the marriage;

(ii) at the time of the marriage, neither party—

• (a) is incapable of giving a valid consent to it in consequence of unsoundness of mind; or
• (b) though capable of giving a valid consent, has been suffering from mental disorder of such a kind or to such an extent as to be unfit for marriage and the procreation of children; or
• (c) has been subject to recurrent attacks of insanity;

(iii) the bridegroom has completed the age of twenty-one years and the bride, the age of eighteen years at the time of the marriage;

(iv) the parties are not within the degrees of prohibited relationship unless the custom or usage governing each of them permits of a marriage between the two;

(v) the parties are not sapindas of each other, unless the custom or usage governing each of them permits of a marriage between the two;