Question
Using Dobereiner’s law of triads, find the missing number.
$\frac{ Li }{7}, \stackrel{ Na }{\ldots \ldots}, \frac{ K }{39}$
$\frac{ Li }{7}, \stackrel{ Na }{\ldots \ldots}, \frac{ K }{39}$
✓
Answer
Using Dobereiner’s law or triads, the missing number is
$\frac{ Li }{7}, \frac{ Na }{23}, \frac{ K }{39}$
$\frac{ Li }{7}, \frac{ Na }{23}, \frac{ K }{39}$
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