12. (1) The ²[office of Mayor and seat of a Commissioner] shall become vacant if- (a) he fails to make the oath referred to in section 7 within the period of thirty days after the date of publication of his name in the official Gazette, unless the Government, for good cause shown, extends the period; (b) he resigns his seat under section 9; (c) he is removed from his seat under section 10; (d) he becomes subject to any of the disqualifications mentioned in section 11 (2); or (e) he dies. (2) and (2A) [Omitted by section 13 of the Khulna City Corporation (Amendment) Act, 1993 (Act No. X of 1993).] (3) If any question arises as to whether ³[the Mayor or a Commissioner] has, after his election, become subject to any of the disqualifications mentioned in section 11(2), the Chief Executive Officer shall refer the question to the District Judge of Khulna and, if the District Judge is of the opinion that ⁴[the Mayor or the Commissioner] has become subject to any such disqualification, ⁵[the Mayor or the Commissioner] shall cease to be ⁶[the Mayor or a Commissioner], and his seat shall become vacant, with effect from the date on which the opinion is given. ⁷[(4) Vacation of office of the Mayor or the vacation of seat of a Commissioner shall be notified in the official Gazette.]