Which of the following is always true when a substance undergoes a physical change?

a. the composition changes.

b. a change in color occurs.

c. no new substance is formed.

d. its specific gravity remains the same.

Write the symbol are element X, which has 22 electrons and 22 neutrons.

Why do a planets speed change in orbit

When a sample of Mg (s) reacts completely with O2 (g), the Mg (s) loses 5.0 moles of electrons. How many moles of electrons are gained by the O2 (g) ?

Which process releases 2260 joules of heat energy per gram of water into the environment

Newton's First Law of Motion means that it will take a force to start and stop an object in motion.

A very small equilibrium constant means ... a. an equal amount of reactants and products c. more products b. more reactants d. system isn't at equilibrium

What is in a banana? give me specifics?!

When 17.28 mL of a 0.078 M aqueous solution of Na2SO4 is combined with 11.30 mL of a 0.20 M aqueous solution of NaCl and 7.84 mL of a 0.26 M aqueous solution of KCl, what is the total concentration of Na + in the combined solution?

What mass of carbon can 3000 J of energy raise from 12°C to 40°C?

How do you balance __Mg + __HCl - - > __MgCl2 + ___ H2