Question 1

What happens to the total mass during a chemical reaction in a closed container?

Accepted Answer

The total mass remains constant.

Answer

The mass of the reactants is greater than the products.

Answer

The reactants lose mass.

Answer

The products gain mass from the surroundings.

Question 2

What is the overall charge of an atom with 11 protons and 11 electrons?

Accepted Answer

Neutral

Answer

+1

Answer

+11

Answer

-11

Question 3

Which subatomic particle has almost no mass?

Accepted Answer

Electron

Answer

Nucleus

Answer

Neutron

Answer

Proton

Question 4

How many neutrons are present in an atom with atomic number 19 and mass number 39?

Accepted Answer

20

Answer

39

Answer

19

Answer

58

Question 5

Which type of radiation can be stopped by a sheet of paper?

Accepted Answer

Alpha

Answer

Gamma

Answer

Beta

Answer

X-rays

Question 6

Which pair represents isotopes?

Accepted Answer

Chlorine-35 and Chlorine-37

Answer

Sodium and Potassium

Answer

Carbon and Oxygen

Answer

Helium and Neon

Question 7

Why do isotopes of an element have different masses?

Accepted Answer

Different numbers of neutrons

Answer

Different atomic numbers

Answer

Different electron arrangements

Answer

Different numbers of protons

Question 8

One atomic mass unit is approximately equal to the mass of what?

Accepted Answer

One proton or one neutron

Answer

One atom

Answer

One electron

Answer

One molecule

Question 9

According to Bohr's model, how do electrons move?

Accepted Answer

In fixed energy levels.

Answer

Randomly throughout the atom.

Answer

Inside the nucleus.

Answer

Without energy.

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