Answer:
1.75 mole of Sn
Step-by-step explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
Sn + 2HF —> SnF2 +H2
From the balanced equation above,
1 mole of Sn reacted with 2 moles of HF.
Therefore, Xmol of Sn will react with 3.5 moles of HF i.e
Xmol of Sn = 3.5/2
Xmol of Sn = 1.75 mole
Therefore, 1.75 mole of Sn is needed to react with 3.5 moles of HF