All atoms of the same element must have the same number of

Protons

Explanation: The number of protons corresponds to the atomic number.

Explanation:

Atomic number is defined as the total number of protons present in an element.

Each element of the periodic table has different atomic number because each of them have different number of protons.

For example, atomic number of Na is 11, and atomic number of Ca is 20.

On the other hand, atomic mass is the sum of total number of protons and neutrons present in an atom.

For example, atomic mass of nitrogen is 14 that is, it contains 7 protons and 7 neutrons.

Thus, we can conclude that all atoms of the same element must have the same number of protons.

here we know that ball will drop down by total distance 3.2 m

so here we know that

now using kinematics

now in the same time it will cover horizontal distance of 0.75 m

so speed of the ball will be

continuous conducting path for current, power supply