Which of these indicate that a chemical reaction has occurred? a.) formation of a gas. b.) boiling of a substance. c.) melting of a substance . d.) freezing of a substance.

answer: gold foil experiment - he shot alpha particles at a gold foil

explanation:

rosa was looking for patterns to predict the products of chemical reactions. she recorded three similar decomposition reactions in the table.she should record 2licl + 3o2.

in the last row of the table. it is the thermal decomposition of chlorate lithium, hence, she should record these products as: lithium chloride ( 2licl ) and oxygen ( 3o2 )   2 > 2 licl + 3o2.