Can someone answer this question please. Is this a physical change or chemical change?

What semimetal can form four single covalent bonds.

Which of the following statements about acidic water is true? a. acid has no effect on the h, o molecules. b. the solution contains a larger number of oh ions than h, o ions. c. the solution contains a larger number of h, o ions than qh ions. d. the solution contains an equal number of h, o ions and oh ions. none of the above e.

He table below gives the atomic mass and relative abundance values for the three isotopes of element m. relative abundance (%) atomic mass (amu) 78.99 23.9850 10.00 24.9858 11.01 25.9826 what is the average atomic mass (in amu) of element m? 2.86 5.36 24.30 24.98