Question

Platinum (Pt) is in the 78th position in the periodic table. A neutral atom of the element that comes just before platinum in the periodic table has electrons and protons

Answer 1

The position of elements of the periodic table is organized according to the atomic number.
Before 78th position, there is 77th position which is belonged to Iridium (Ir). If the atom is neutral then there is no charge on it.
That means atomic number = number of protons = number of electrons.

Hence, 77th position has 77 of protons and 77 of electrons.

Answer 2

The ansseer is Iridium.

The atomic number of iridium is 77 and it comes just before platinum (atomic number = 78).

In iridium,

The number of electrons = no. Of protons = 77.
The no. Of electrons and the no. Of protons is same as atomic number.