Question 1: Which of the following is not a characteristic of strong acids? They react with most metals to form a salt and hydrogen gas.
They fully ionise in water to form their conjugate base.
They form aqueous solutions with a pH greater than 7.
They conduct electricity in aqueous solution.

there is none because earth is stationary and flat.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.