25.0 mL of 0.275 M NaBrO₃ is added to a 150.0 mL solution containing 0.175 M KBr and 0.450 M HClO₃. The bromate and bromide ions react to produce bromine liquid. After the reaction, what are the concentrations of all the ions in the solution? Make sure the solution is electrically neutral by checking your concentrations.

A 0.175 g sample of a specific semimetal M heated in air yielded the corresponding oxide MO₂. The reaction required 17.50 mL of 0.550 M MnO₄⁻ when the oxide was dissolved in aqueous acid and titrated with KMnO₄. 

H₂MO₃(aq) + MnO₄⁻(aq) → Mn²⁺(aq) + H₂MO₄(aq) (unbalanced)

Give the name of the semimetal M.

The Winkler method can be used to determine the amount of dissolved oxygen in water samples by converting dissolved oxygen to MnO₂ with MnSO₄ and reacting it with NaOH and KI. The solution is then acidified for the oxidation of I⁻ to I₃⁻ by MnO₂ to occur. The amount of I₃⁻ formed is determined by titration with S₂O₃²⁻. The unbalanced equations are

Mn²⁺(aq) + O₂(g)→ MnO₂(s)

MnO₂(s)+ I⁻(aq) →Mn2+(aq) + I₃⁻(aq)

When 0.1578 g of a water sample is analyzed, the reaction needs 17.55 mL of 0.1300 M Na₂S₂O₃. Calculate the mass percent of oxygen in the sample.

What is the balanced equation for the following redox reaction? 

Cr(s) + NO₃^-(aq) → NO(g) + Cr³⁺(aq)

How much 0.384 M NaNO₃ solution in mL is needed to thoroughly react with 4.23 g of Cr?