TOKYO, Aug 10 (Reuters) - Japan's Nikkei stock average hit a 10-month high on Monday after better-than-expected Japanese and U.S. data underpinned hopes that both economies are on the mend, with exporters also gaining on a weaker yen. Mitsubishi Chemical Holdings, Japan's largest chemical firm, surged 5.2 percent after the Nikkei business daily said it is in talks to acquire resin maker Mitsubishi Rayon in a deal worth up to 200 billion yen ($2.1 billion). Mitsubishi Rayon soared 20.9 percent. The benchmark Nikkei rose 1.4 percent or 147.90 points to 10,599.99 after climbing as far as 10,585.37, its highest since Oct. 6. The broader Topix rose 1.6 percent to 971.62. (Reporting by Elaine Lies)