Answer:
A. They have the same atomic numbers.
Explanation:
Elements are defined based on the atomic number, which is the number of protons in the nucleus: this means that atoms of the same element have always the same number of protons in their nuclei (and so, always the same atomic number).
The other choices are wrong because:
B. They have the same average atomic masses. --> this is false for isotopes, which are atoms of the same element having a different number of neutrons. Since the atomic mass is calculated from the sum of the masses of protons and neutrons in the nucleus, two isotopes of the same element have different atomic mass
C. They have the same number of electron shells. --> this can be false when an atom of an element loses/gains an electron, becoming an ion: in that case, the number of electron shells can change, since the number of electrons has changed.
D. They have the same number of electrons in their outermost shells. --> this is also false in case one of the atoms is an ion, since the number of electrons is different.
Answer:
At the instant shown in the diagram, the car's centripetal acceleration is directed is discussed below in detail.
Explanation:
The direction of the centripetal acceleration is in a circular movement is forever towards the middle of the roundabout pathway. In the picture displayed, the East direction is approaching the center. So, the course of the car's centripetal acceleration is (H) toward the east.
The acceleration of gravity (on Earth) is 9.8 m/s² downward.
This means that every falling object gains 9.8 m/s more downward speed
every second that it falls.
In 5 seconds of falling, it gains (5 x 9.8 m/s) = 49 m/s of downward speed.
If it was already descending at 2.0 m/s at the beginning of the 5 sec,
then at the end of the 5 sec it would be descending at
(2 m/s + 49 m/s) = 51 m/s .
