Question

this element has one more proton than caesium (cs). this element has 5 protons in its nucleus. the atomic number of this element is 10. this element has 54 electrons surrounding its nucleus. this element has 4 more protons than silicon (si). this element has 2 fewer electrons than strontium (sr) surrounding its nucleus. the atomic number of this element is 31. this element has one less proton than arsenic (as).

Explanation:

Step1: Recall atomic - number concept

The number of protons in an atom is equal to its atomic number. Also, in a neutral atom, the number of electrons is equal to the number of protons.

Step2: Analyze each statement

• For "This element has one more proton than Caesium (Cs)": Cs has an atomic number of 55, so the element is 56 (Barium, Ba).
• "This element has 5 protons in its nucleus": Atomic number 5 is Boron (B).
• "The atomic number of this element is 10": Neon (Ne).
• "This element has 54 electrons surrounding its nucleus": In a neutral atom, number of electrons = number of protons, so atomic number 54 is Xenon (Xe).
• "This element has 4 more protons than Silicon (Si)": Si has atomic number 14, so 14 + 4=18, which is Argon (Ar).
• "This element has 2 fewer electrons than Strontium (Sr) surrounding its nucleus": Sr has atomic number 38, so 38 - 2 = 36, which is Krypton (Kr).
• "The atomic number of this element is 31": Gallium (Ga).
• "This element has one less proton than Arsenic (As)": As has atomic number 33, so 33 - 1=32, which is Germanium (Ge).

Answer:

10: B
11: Ne
12: Xe
13: Ar
14: Kr
15: Ga
16: Ge