Chemistry

What are isotopes?

• They are negatively-charged particles

• They are positively-charged particles

• They are atoms with the same atomic number but different number of neutrons.

• They are atoms with the same number of neutrons but different atomic number.

A student accidentally mixed iron nails, water, marbles, and sand. What separation techniques must the student do in chronological order to separate the components completely?

• Magnetic separation, filtration, and mechanical picking

• Distillation, filtration, and mechanical picking

• Filtration, decantation, and mechanical picking

• Evaporation, distillation, and decantation

What is the molar mass of the compound formed between bromine and calcium?

• 198.99 g/mol

• 197.89 g/mol

• 199.89 g/mol

• 189.98 g/mol

When does an atom become positively charged?

• If it gains a proton

• If it gains an electron

• If it loses a proton

• If it loses an electron

Which of the following describes a chemical property?

• Flourine is a pale yellow gas.

• Flourine reacts with most substances.

• Flourine melts at -220oC.

• Flourine boils at -188oC.

Which of the following is an example of an empirical formula?

• H2O2

• C2H4O2

• CH4O

• N2O4

Which of the following is NOT an example of a chemical change?

• Sublimation of naphthalene balls

• Digestion of food

• Burning of wood

• Burning of wood

Which of the following oxyanions can form a 1:1 ratio compound with barium?

• Nitrate

• Chlorite

• Acetate

• Carbonate

Which of the following principles is NOT included in Dalton's Atomic Theory?

• When matter undergoes changes, whether physical or chemical, the atoms are merely

  rearranged.

• Atoms of different element that are identical can combine to form compounds.

• Atoms are neither created nor destroyed.

• All matter is composed of tiny, indivisible particles called atoms.

Which of the following statements is TRUE about the atoms of 138Ce and 136Ce?

• They have the same number of neutrons but different number of protons.

• They have the same number of protons but different number of neutrons.

• They have the same number of electrons but different number of protons.

• They have the same number of neutrons but different number of electrons.