Which of there is an indication that a chemical reaction has occurred?

a. freezing of substance

b. a change in color of a substance

c. melting of a substance

d. boiling of a substance

Without looking at the periodic table write the expected outer electron configuration for each of the following elements: A. Group 7, fourth period B. Group 3, fifth period C. Group 12, sixth period

How many grams are in 1.0 moles of baking soda?

General term for substances formed when metals and nonmetals combine

Determine the enthalpy for this reaction: 2naoh (s) + co2 (g) →na2co3 (s) + h2o (l) express your answer in kilojoules per mole to one decimal place.

What is planck's theory?

A population of crabs live on a light-colored sandy beach. In this environment there is a population of birds that eat the crabs. One year, there is a volcanic eruption near the beach and dark volcanic ash covers the beach.

It would take one light year to travel to the sun? True or false?

A specific, electrically neutral atom of boron has 5 protons, 5 electrons, and 6 neutrons. what is the mass number of this atom of boron? 6 5 11 16

When does hail happen?

For the reaction, calculate how many moles of the product form when 0.012 mol of O2 completely reacts. Assume that there is more than enough of the other reactant. 4Al (s) + 3O2 (g) →2Al2O3 (s) Express your answer using two significant figures.