JAMB - Chemistry (2011 - No. 5)
The relative atomic mass of a naturally occurring lithium consisting of 90% \(^7 _3\)Li and \(^6 _3\)10% Li is
6.9
7.1
6.2
6.8
คำอธิบาย
R.A.M = m\(_1 \alpha_1\) + m\(_2 \alpha_2\)
= 7(90/100) + 6(10/100)
= 6.3 + 0.6
= 6.9