Zn gives H₂ gas with H₂SO₄ and HCl but not with HNO₃ because:

Zinc reacts with non-oxidizing acids like HCl and H₂SO₄ to evolve dihydrogen gas because Zinc has a lower standard reduction potential ($E^0 = -0.76 V$) than hydrogen ($E^0 = 0.00 V$), allowing it to reduce $H^+$ ions . However, $HNO_3$ is a strong oxidizing agent. When metals (with exceptions like Mg and Mn with very dilute acid) react with $HNO_3$, the hydrogen initially produced is oxidized to water, while the nitrate ion ($NO_3^-$) is reduced to various nitrogen oxides ($NO, NO_2$, etc.) . Thermodynamically, the reduction of the nitrate ion occurs in preference to the reduction of the hydronium ion ($H^+$) to $H_2$ gas.