The reagent among the following that does not reduce an aryl nitro compound to an amine is:

1. H₂(excess) / Pt

2. LiAlH₄ in ether

3. Fe and HCI

4. Sn and HCI

In nitration of benzene using a mixture of conc. H₂SO₄ and conc. HNO₃, the species that initiates the reaction is :

1. NO₂
2. NO⁺
3. NO₂⁺
4. NO₂^-