number of protons, neutrons, and electrons?

²H

(Find the atomic number using the Periodic Table. The superscript at the top-left-corner of the symbol is the mass number.)
(Number of protons = No. of electrons = Atomic number)
(Number of neutrons = [Mass number] - [Atomic number])

The atomic number of H is 1. The mass of number of ²H is 2.
Number of protons = No. of electrons = 1
Number of neutrons = 2 - 1 = 1


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¹⁴C

The atomic number of C is 6. The mass number of ¹⁴C is 14.
Number of protons = Number of electrons = 6
Number of neutrons = 14 - 6 = 8


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²³⁸U

The atomic number of U is 92. The mass number of ²³⁸U is 238.
Number of protons = Number of electrons = 92
Number of neutrons = 238 - 92 = 146


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What is the isotope that has 2 neutrons and 1 electron?

Atomic number = 1
Refer to the Periodic Table. It is an isotope of hydrogen (hydrogen-2).


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What is the isotope that has an atomic number of 82 and a mass number of 206

Atomic number = 82
Refer to the Periodic Table. It is an isotope of lead (lead-206).

2H deuterium - The isotope that has 2 neutrons and 1 electron.

14C carbon 14 - used for dating organic material from near the present to about 30,000 years ago. Not one of the two answers.

"238U Urananium 238 the most common isotope of unranium and the one that does not go boom

But not an atomic mass of 206 its 238 because that IS its mass. No remotely stable isotope of uranium has an atomic mass near 206.

I suspect that you have a typo as only uranium has 92 protons and its lightest isotope is 215U with a half life of 2.24 ms which is rather short.

2 - H ; 2 neutrons & 1 electron is 'Heavy hydrogen' otherwise known as 'deuterium.
symbol is '[2/1] - H '.
14 - C ; 6 protons, 8 neutrons, 6 electrons.
238 - U ; 92 protons , 146 neutrons, 92 electrons

A.No. 82 is Lead ( 206-Pb) A lighter isotope of lead. The usual stable isotope is 207 - Pb.
206 Pb ; 82 protons, 124 neutrons, 82 electrons.