. In which reaction is nitric acid acting as an oxidising agent? A. CuO + 2HNO3 → Cu(NO3)2 + H2O B. Cu + 4HNO3 → Cu(NO3)2 + 2H2O + 2NO2 C. Na2CO3 + 2HNO3 → 2NaNO3 + H2O + CO2 D. NaOH + HNO3 → NaNO3 + H2O

B. Cu + 4HNO3 → Cu(NO3)2 + 2H2O

Explanation:

A redox reaction is one in which oxidation and reduction reactions are occuring simultaneously.

In a redox reaction, an oxidizing agent is reduced ( its oxidation state decreases) whereas a reducing agent is oxidized (it's oxidation state increases).

The nitrogen in the nitrate (v) ion, NO3-, exists in the +5 oxidation state. Therefore it would be acting as an oxidizing agent in any reaction in which it's oxidation state becomes less than +5 after the reaction.

Let us then consider each of the reactions:

A. Reaction 1: in this reaction, the oxidation state of nitrogen remains +5 as what is simply an exchange of radicals in a neutralization reaction.

B. Reaction 2: in this reaction, trioxocarbonate (v) acid oxidizes Copper atom to Copper (ii) ion, while itself it is reduced to Nitrogen (IV) oxide. The oxidation state of nitrogen changes from +5 to +4

C. Reaction 3: in this reaction, what occurs is an exchange of radicals by a displacement reaction. The oxidation state of nitrogen remains the same

D. Reaction 4: in the reaction, what occurs is a neutralization reaction, and the oxidation state of nitrogen remains the same.

Therefore, the correct option is B.

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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ill try to . no promises tho.

explanation: