Answer : The excess reagent is,

Explanation : Given,
Mass of NaCl = 4 g
Mass of
= 10 g
Molar mass of NaCl = 58.44 g/mole
Molar mass of
= 169.87 g/mole
First we have to calculate the moles of
and
.
Now we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,
From the balanced reaction we conclude that
As, 1 moles of
react with 1 mole of
So, 0.059 moles of
react with 0.059 mole of
From this we conclude that,
is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Hence the excess reagent is,
