An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.

Question

Two electrons are moving in orbits of two hydrogen like atoms with speeds $3\times10^{5}\,\text{m/s}$ and $2.5\times10^{5}\,\text{m/s}$ respectively. If the radii of these orbits are nearly same then the possible order of energy states are ___ respectively.

Answer 1

Given:

Mass number, A = 81
Number of neutrons = 31.7% more than protons

Step 1: Define variables

Let number of protons = p

Number of neutrons = p + 31.7% of p

Number of neutrons = 1.317p

Step 2: Use mass number relation

Mass number = Protons + Neutrons

81 = p + 1.317p

81 = 2.317p

p = 34.96 ≈ 35

Step 3: Calculate neutrons

Number of neutrons = 81 − 35 = 46

Step 4: Identify the element

Atomic number = 35

Element with atomic number 35 is Bromine (Br)

Final Answer:

The atomic symbol of the element is:

⁸¹₃₅Br

An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.

Solution and Explanation

Top Questions on Atomic Models

Questions Asked in CBSE Class XI exam