Select the correct answer. a student places a sample of white sodium bicarbonate powder in a test tube and heats it. the student observes that the sodium bicarbonate undergoes a chemical change. after the change, what must be true about the substance in the test tube? a. it is not white. b. it is a liquid. c. it is an element. d. it is not sodium bicarbonate.

Answer is: D. It is not sodium bicarbonate.

Balanced chemical reaction of heating sodium bicarbonate:                    2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O.

This is chemical change (chemical reaction), because new substances are formed (sodium carbonate, carbon(IV) oxide and water), the atoms are rearranged, so there is no sodium bicarbonate (NaHCO₃) in the test tube.

D

Explanation:

samuel de champlain. in 1608, king henry iv sponsored pierre dugua, sieur de mons and samuel de champlain as founders of the city of quebec with 28 men. this was the second permanent french settlement in the colony of canada.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.