Exxon Mobil Corp., the No. 1 oil company, said first-quarter earnings rose 51 percent, as it cashed in on strong crude oil and natural gas prices as well as better profits from refined fuels such as gasoline. Exxon Mobil posted record first-quarter income, excluding merger effects, of $5.05 billion, up from $3.35 billion in the year-earlier period. First-quarter revenues rose to $57.28 billion from $54.1 billion a year before. Earnings for the Irving, Texas-based oil company, which last year set a record for the world's highest corporate profits, surpassed most analysts' expectations, helping its stock rise nearly 2 percent on the New York Stock Exchange. Conoco, the No. 4 U.S. oil company, also reported profits that were better than most expected.