In which two types of reactions do opposite chemical changes occur? double replacement and combustion
single replacement and double replacement
synthesis and decomposition
combustion and synthesis

Which statement is true about a catalyst? a: a catalyst decreases the rate of the reaction. b. a catalyst is consumed during a chemical reaction. c. a catalyst lowers the activation energy of a reaction. d. a catalyst increases the reactant concentration during a reaction.

What is the approximate vapor pressure when the gas condenses at 70 degrees celsius

Astring vibrates with a frequency of 10 hz. why can't a person hear the sound waves produced by the vibrating string, no matter how large the amplitude of the waves? out! this is homework and due tomorrow! you so much!