The alloy bronze contains copper and: MCQ with Answer and Explanation

Explanation:
Alkenes follow CₙH₂ₙ. C₂H₄ (ethene) fits n=2 giving H=4. C₂H₆ and CH₄ are alkanes (CₙH₂ₙ₊₂); C₃H₈ is propane (alkane). Alkenes contain a carbon-carbon double bond.

Explanation:
In an electrochemical cell, reduction (gain of electrons) always occurs at the cathode, regardless of whether the cell is electrolytic or galvanic. At the anode, oxidation (loss of electrons) occurs. Memory aid: 'RED CAT' (REDuction at CAThode), 'AN OX' (OXidation at ANode). In electrolysis, the cathode is connected to the negative terminal of the battery, attracting cations which get reduced.

Explanation:
Cu + 4HNO₃ (conc.) → Cu(NO₃)₂ + 2NO₂ + 2H₂O. Dilute HNO₃ gives NO instead of NO₂. Copper does not produce H₂ with HNO₃ because HNO₃ is an oxidizing acid.