SHANGHAI—Bonds issued by heavily indebted developer China Evergrande Group plunged on Monday over growing investor worries about the company’s ability to pay its debts, prompting China’s stock exchanges to halt trading. The Shanghai Stock Exchange said in a statement that it had temporarily suspended trading in China Evergrande Group’s 6.98 percent July 2022 corporate bond following “abnormal fluctuations.” The exchange had also suspended trading in the bond on Friday, Sept. 3. Shanghai exchange data showed the bonds sliding more than 25 percent to a low of $6.22 after the resumption of trade on Monday afternoon, reflecting investor doubts that Evergrande will be able to repay investors in full on the bond’s maturity next year. The company’s 5.9 percent May 2023 Shenzhen-traded bond, which was also suspended from trading, fell more than 35 percent after trading resumed on Monday afternoon. The slump in bond prices on Monday, comes after China Securities …