Question

2AgCl+4NaOH+Zn---->Na2Zn(OH)4+2Ag+2NaCl which one of them is the limiting reagent we are not given any amounts for the reactants?

Answer 1

When no masses are given for the reactans, go by lowest number of moles as an indicator of a possible limiting reagent.

In your case, the balanced chemical equation is

`color(red)(2)AgCl + color(green)(4)NaOH + Zn -> Na_2Zn(OH)_4 + 2Ag + 2NaCl`

For the reactants, you've got 1 mole of zinc, `color(red)(2)` moles of silver chloride, and `color(green)(4)` moles of sodium hydroxide required for the reaction to take place.

If you go by moles, the species with the fewest number of moles can be treated as a limiting reagent; in your case, since zinc has the fewest number of moles that take part in the reaction, zinc will act as a limiting reagent.

This is all speculation, however, since you can't actually tell what the limiting reagent is, or even if you have one, without information on the masses of the reactants.