When substances go through chemical changes, which of the following will always happen? a. one or more substances with different chemical properties will form. b. one or more substances will be completely destroyed. c. a poisonous gas will form or a white solid will precipitate. d. all of these

A.  One or more substances with different chemical properties will form.

Explanation:

Chemical change is defined as a change in which rearrangement of atoms take place and leads to formation of new substance. Thus as new substances are formed, the chemical properties of the products will alwys be different from the chemical properties of reactants.

Physical change is defined as a change in which change in shape, size or state of the substance takes place. No new substance is formed.

Chemical change may involve following changes:

1) Formation of precipitates

2) Absorption or evolution of heat

3) Color change

4) Evolution of gas

gold is my favorite solid.

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.