April 30 (Reuters) - Top U.S. oil producer Exxon Mobil Corp on Friday posted its first profit in five quarters, as higher oil and gas prices offset costs from a deep freeze in February. Net income attributable to Exxon was $2.73 billion, or 64 cents per share, in the first quarter, compared with a loss of $610 million, or 14 cents per share, a year earlier.