#### Answer

There are 0.0626 mol of $NaHCO_3$ in Alka-Seltzer tablets.

#### Work Step by Step

1. Calculate the molar mass $(NaHCO_3)$:
22.99* 1 + 1.008* 1 + 12.01* 1 + 16.00* 3 = 84.01g/mol
2. Calculate the number of moles $(NaHCO_3)$
$n(moles) = \frac{mass(g)}{mm(g/mol)}$
$n(moles) = \frac{ 5.26}{ 84.01}$
$n(moles) = 0.0626$
Or, you can use other method:
$5.26 g \times \frac{1 mol}{84.01g} = 0.0626 mol$