A newly admitted partner has the right to-

The correct option is: Share the profit of firm after his admission.

Step-by-Step Explanation:

1. Nature of Partnership Admission: when a new partner is admitted into an existing partnership firm, a new partnership agreement (deed) is created, and the old partnership is reconstituted. The new partner brings in capital and sometimes goodwill in exchange for specific rights in the firm.

2. Rights of a Newly Admitted Partner: Upon admission, a new partner generally acquires two main rights:
- Right to share the future profits of the firm: The new partner is entitled to a share of the profits and losses generated by the business operations after the date of their admission.
- Right to share the assets of the firm: The new partner gets a share in the assets of the firm, which are used to generate future earnings.

3. Why the other options are incorrect:
- Share the assets of the firm before his admission: A partner cannot lay claim to assets in a way that ignores the liabilities or claims existing before their entry; their rights to assets and profits start from the date of admission.
- Share the general reserve already appearing in the Balance Sheet before his admission: Any accumulated profits, reserves, or losses that existed prior to the partner's admission belong solely to the old partners in their old profit-sharing ratio. These are distributed or adjusted among the old partners before the new partner is officially admitted.
- Demand extra-profit than his agreed share if business makes huge profits: A partner is strictly bound by the profit-sharing ratio agreed upon in the partnership deed, regardless of how high the profits are.