The General Services Division of the Budget and Control Board shall, when necessary, execute a certificate of exemption from taxation when a certificate is required for Federal tax purposes for or on behalf of political subdivisions that purchase property from or through the General Services Division and the certificate so executed shall then constitute the certificate of the political subdivision. The General Services Division shall accept the political subdivision's requisition or purchase order as conclusive proof that the property so requisitioned or purchased is for the exclusive use of the political subdivision.