An element has 18 electrons, and 20 .neutrons. Its charge is —2. What is its mass number?a)32b)38c)39d)40Correct answer is option 'C'. Can you explain this answer?

Question

An element has 18 electrons, and 20 .neutrons. Its charge is &mdash;2. What is its mass number?a)32b)38c)39&#8203;d)40Correct answer is option 'C'. Can you explain this answer?

Answer

Atomic mass of element = Number of proton + Number of neutron

Number of proton = Number of electron

It is given that charge on element is -2 it means it is anion.

Atomic mass = 18 + 20 = 38 Answer

Answer

Answer is 'd' becoz charge is -2 so the total electron is 20.. No of elctron = no. Of proton 20=20 Mass no. = no. Of proton + no of neutron = 20+20 =40

Answer

B

Answer

The maximum number of atomic orbitals associated with a principal quantum number 5 is 25.

Explanation:

Principal Quantum Number:
The principal quantum number (n) describes the energy level of an electron in an atom. It determines the size and energy of the orbital. The value of n can be any positive integer starting from 1.

Number of Orbitals:
The number of orbitals associated with a given principal quantum number (n) can be calculated using the formula 2n^2. This formula gives the maximum number of orbitals that can exist in a given energy level.

Calculation:
For n = 5, the maximum number of orbitals can be calculated as follows:

Number of orbitals = 2n^2
= 2 * 5^2
= 2 * 25
= 50

However, it is important to note that the maximum number of orbitals in an energy level is limited by the maximum number of electrons that can occupy that energy level. Each orbital can hold a maximum of 2 electrons, and the total number of electrons in an energy level is given by 2n^2.

Maximum Number of Electrons:
The maximum number of electrons that can occupy an energy level is given by the formula 2n^2, where n is the principal quantum number.

For n = 5, the maximum number of electrons can be calculated as follows:

Number of electrons = 2n^2
= 2 * 5^2
= 2 * 25
= 50

Since each orbital can hold a maximum of 2 electrons, the maximum number of orbitals associated with a principal quantum number 5 is 25 (50/2).

Therefore, the correct answer is option B) 25.

Answer

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