Question

a certain amount of metal whose equivalent mass is 28 displaces 0.7 L of H2 at STP from an acid , hence the mass of the element is?

Answer 1

1 mole of Hydrogen at STP occupies 22.4 litres volume.
Number of moles of 0.7 litres of Hydrogen at STP is 0.7/22.4 = 0.0313 moles

Weight of element (x) = Moles of Hydrogen times equivalent weight of metal times mass of Hydrogen
x = 0.0313*28*2
x = 1.7528 grams

Answer 2

Explanation:

here is your answer

n-factor of hydrogen is 2 as charge on hydrogen changes from +2 to 0 in above reaction