5. Power-of-attorney of married woman 6[A married woman of full age shall, by virtue of this Act, have power, as if she were unmarried,] by a non-testamentary instrument, to appoint an attorney on her behalf, for the purpose of executing any non-testamentary instrument or doing any other act which she might herself execute or do; and the provisions of this Act, relating to instruments creating powers-of-attorney, shall apply thereto. This section applies only to instruments executed after this Act comes into force.