पदार्थ की वह कौन सी अवस्था है जिसका न तो निश्चित आयतन होता है और न ही निश्चित आकार होता है?

Substances A and B together form C, and substances D and E together form F. The newly formed substances C and F have the following properties: (a) C exhibits the properties of both A and B. (b) D and E can be separated from F by electrochemical methods only. Which of the following statements is true?

Which of the following is considered a chemical change?