These are the first 20 elements on the periodic table. Which of these elements had 20 protons in its nucleus (atomic number = 12)? 1. He 2. S 3. Mg 4. C HYDROGEN PERIODIC TABLE OF ELEMENTS 1-20 H He 40 UMal BERYLLIUM BORON CARBON NITROGEN OXYGEN FLUORINE NEON Li Be B @01 10 01 MAGNESIUM ALUMINUM Ne 218 ARGON 12.01 Iol Juloo 1400 Sodium SILICON PHOSPHORUS SULFUR CHLORINE Na Mg Al Si Eode 20 POTASSIUM CALCIUM CI Ar 30 42 07 Ca cia
The Correct Answer and Explanation is:
Which of these elements has 20 protons in its nucleus (atomic number = 20)?
Options:
- He (Helium)
- S (Sulfur)
- Mg (Magnesium)
- C (Carbon)
✅ Correct Answer: None of the options provided have an atomic number of 20.
However, based on the periodic table shown in your image, the element Calcium (Ca) has 20 protons and therefore an atomic number of 20.
Let’s analyze the options to understand why none are correct:
- He (Helium) – Atomic number 2, so it has 2 protons.
- S (Sulfur) – Atomic number 16, so it has 16 protons.
- Mg (Magnesium) – Atomic number 12, so it has 12 protons.
- C (Carbon) – Atomic number 6, so it has 6 protons.
Why Calcium is the Right Answer (Even Though It’s Not an Option):
The atomic number of an element indicates the number of protons in its nucleus. Each element has a unique atomic number:
- Hydrogen (H) = 1
- Helium (He) = 2
- …
- Calcium (Ca) = 20
This is evident in the periodic table image you provided. Calcium is located in the second group of the fourth period. It is an alkaline earth metal and is essential in biological systems, especially in bone formation and nerve function.
Therefore, the correct element with 20 protons is Calcium (Ca) — but it was not listed among the multiple-choice options.
Summary:
- None of the given options (He, S, Mg, C) have 20 protons.
- The element that has 20 protons is Calcium (Ca).
- This appears to be a trick or flawed question due to incorrect options.
