Answer:
D
Explanation:
you need battery, light bulb and wire in a close circuit
The balanced half-reaction: Cr²⁺⁺(aq) → Cr⁴⁺(aq) + 2e⁻.
Chromium(II) cations two electrons and became chromium(IV) cations.
<span>Oxidation
reaction is increasing of oxidation number of element, because element or
ion lost electrons in chemical reaction.
</span><span>Reduction is lowering
oxidation number because element or ions gain electrons.</span>
Answer:
Sulfuric acid + Zinc = reactant
Zinc sulfate + hydrogen = product
Lead oxide + carbon = reactant
lead + carbondioxide = product
Explanation:
Chemical equation:
Sulfuric acid + Zinc → Zinc sulfate + hydrogen
H₂SO₄ + Zn → ZnSO₄ + H₂
In this reaction sulfuric acid and zinc react to produce the zinc sulfate and hydrogen. That's why sulfuric acid and zinc are reactant. While zinc sulfate and hydrogen are products.
2nd reaction:
Lead oxide + carbon → lead + carbondioxide
2PbO + C → 2Pb + CO₂
In this reaction Lead oxide and carbon react to produce the lead and carbondioxide. That's why Lead oxide and carbon are reactant. While lead and carbondioxide are products.
The pairs are:
K, Kr - Same period
Be, Mg - Same group
Ni, Tc - Both are transition metals
B, Ge - Both are metaloids
Al, Pb - Both form inert oxides
