Which best describes eras and periods? Eras have a smaller time span than periods. Eras and periods are independent of each other. Eras and periods both appear at the start of the Cambrian period. Eras were more recently established on the time scale than periods.

it is b that is the answer.

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.