Question

An element with mass number 181 contains 32% more neutrons as compared to protons. What is the symbol of that element?
$(1)Pt$
$(2)Pd$
$(3)Au$
$(4)Hg$

Answer 1

An atom is the basic unit of all elements and compounds. It consists of 2 parts-A nucleus in the centre of the atom and electrons surrounding the nucleus. The nucleus is made up of protons and neutrons. Electrons are negatively charged, protons are positively charged and neutrons are neutral species. The Atomic number is the number of protons which is also equal to the number of electrons in a neutral atom. Atomic Mass or Mass number is defined as the sum of the number of protons and neutrons in the nucleus.

Complete answer:
In the question we are given Mass number=181=Number of protons +Number of Neutrons
Let us assume Number of Protons $= a$
It is given that number of neutrons is $32\%$( 32/100=0.32) more than the number of protons, so the number of neutrons will be $= a + 0.32a = 1.32a$
Now we know when we add the number of protons and neutrons we get the mass number which in question is given to be 181.
Mass Number $= a + 1.32a = 2.32a = 181$
Therefore, $a = 78.02 \sim 78$
It means we have 78 protons in the atom. And the atom with 78 protons/Atomic number is Platinum (Pt) and hence option (1) is correct.

Note:
Platinum belongs to the d block of the periodic table. Thus it is considered a transition Metal. It is solid at room temperature. It is a soft, heavy, dense, malleable, ductile, precious silver white metal that is resistant to corrosion and other reagants.It has a High melting point. It has high resistance to reagents and thus considered to be “noble metal”.