Question

An element has mass number 39 and atomic number 19. The number of protons and electrons in this element is

(a) 19 and 19 respectively
(b) 19 and 39 respectively
(c) 39 and 19 respectively
(d) 19 and 30 respectively


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Answer 1

Answer:

39

Explanation:

A neutron atom of potassium has an atomic number of 19 and an atomic mass number of 39.

Answer 2

Given:

An element with mass number 39 and atomic number 19.

To Find:

The number of protons and electrons in this element.

Solution:

In any atom Number of protons and number of electrons is same as the atomic Number of atom.

=> No. of Protons = Atomic number

=> No. of protons = 19

=> No. of electrons = 19

Also,  

Mass no. = No. of Protons + No. of Neutrons

Hence, Number of protons and electrons are 19 each.

=> option(a) is correct