Element X has two naturally occurring isotopes

CHEMISTRY · Single correct · A Level · Chemistry · Atomic structure · Atomic structure

Problem

Element X has two naturally occurring isotopes,

^{64}\text{X}

and

^{66}\text{X}

. Their relative abundances are 30.0\% and 70.0\%, respectively. If the abundance of

^{66}\text{X}

decreases while that of

^{64}\text{X}

increases, how will the average atomic mass of X change? (a) It will increase. (b) It will remain the same. (c) It will decrease. (d) It cannot be predicted without knowing the total number of atoms.

Related theory

Subatomic Particles
Atomic Structure
Atomic number, isotopes and isobars
Structure of Atom
Isotopes
The nuclear atom

Browse the problem library