Responses
20
20
19
19
39
39
58
11 answers
The mass number of an atom is the sum of its protons and neutrons. In this case, the atomic model shows:
To calculate the mass number:
Mass number = Protons + Neutrons
Mass number = 19 + 20 = 39
So, the mass number of the atom is 39.
Ammonia (NH₃) consists of one nitrogen atom and three hydrogen atoms. In the molecular model, this can be represented as:
Therefore, the correct option is: one blue sphere and three white spheres.
In a ball-and-stick model, the sticks represent the bonds between atoms. Therefore, the correct answer is:
bonds between atoms.
Potassium (K) and nickel (Ni) are in the same row (or period) of the periodic table, which means they have the same number of electron shells.
Therefore, the correct response is:
They have the same number of electron shells.
In a lithium-ion battery, lithium ions move between the anode and cathode during discharge and recharge, but the lithium atoms themselves are not created or destroyed in the process. Instead, they merely shift back and forth. Therefore, the correct statement is:
A new substance is formed as the battery is used.
This is because, during the discharge process, lithium combined with other materials in the battery, undergoing a chemical reaction that can produce new compounds.
To determine the total number of atoms in the formula Na₂HPO₄, we can break it down:
Now, we add them up:
2 (Na) + 1 (H) + 1 (P) + 4 (O) = 8 atoms
So, the correct answer is eight.
