A5-kilogram rock is perched on a cliff 6 meters above a
lake. how much gravitational potential energy does the rock
have?
oa) 30 j
o b) 90 j
oc) 147
od) 294

294 J

Explanation:

Using E = m g h

E = 5 * 9.8 * 6

E = 294 J

The correct answer is option D.

Explanation:

Cobalt and Nickel both are transition metals which means that their last electron enter d-orbitals.

These two elements have similar atomic masses but differ in the atomic number.

Atomic number is equal to the number of protons or electrons present in that element.

Atomic number = number of protons =  number of electrons

Atomic Mass is the sum of protons and neutrons in an element

Atomic mass = Number of protons + Number of neutrons

Atomic Number = 27

Number of protons = 27

Atomic mass = 59

Number of neutrons = 59 - 27 = 32

Hence, Number of protons in this element is 27 and number of neutrons are 32.

Atomic Number = 28

Number of protons = 28

Atomic mass = 59

Number of neutrons = 59 - 28 = 31

Hence, Number of protons in this element is 28 and number of neutrons are 31.

Hence, the correct answer is option D.