Correct Answer: C. invertase

Correct Answer: D. 2.00mol/dm³

Correct Answer: C. 3

Correct Answer: B) B

Correct Answer: B) -3, +5

Explanation

For NO3-

N+3(-2)=-1

N-6=-1

N=-1+6

N=+5

The oxidation states of ammonium nitrate=-3,+5

Correct Answer: B) is at the bottom of the activity series

Correct Answer: B) 10 mol H₂

Explanation

To answer this question, we need to understand the balanced chemical equation for the formation of water from hydrogen and oxygen:

\(2H_2 + O_2 \rightarrow 2H_2O\)

This balanced equation tells us that 2 moles of hydrogen molecules (H\(_2\) react with 1 mole of oxygen molecules (O\(_2\) to produce 2 moles of water molecules (H\(_2\)O).

Now, we are given that there are 5 moles of O\(_2\) molecules. According to the balanced equation, 2 moles of H\(_2\) are required for 1 mole of O\(_2\). Therefore, to react with 5 moles of O\(_2\), we would need:

\(5 \text{ moles of } O_2 \times \frac{2 \text{ moles of } H_2}{1 \text{ mole of } O_2} = 10 \text{ moles of } H_2\)

So,10 moles of H\(_2\) are needed to convert 5 moles of O\(_2\) molecules to water, which corresponds toOption B.

Correct Answer: D. Potassium fluride reduces the temperature at which sodium chloride fuses

Correct Answer: C. MCl3

Correct Answer: D) catalyst

Explanation

A chemical reaction's activation energy is the minimum energy required for the reactants to transform into products. It serves as an energy barrier that must be overcome for the reaction to occur. In the given question, we need to identify which option reduces the activation energy of a chemical reaction.

Option A: Freezing mixture - A freezing mixture is typically used to lower the temperature of a system. Lowering the temperature often slows down chemical reactions, and does not reduce the activation energy.

Option B: Reducing agent - A reducing agent is a substance that donates electrons in a redox reaction, causing the reduction of another species. While it plays a crucial role in redox reactions, it does not directly affect the activation energy of a general chemical reaction.

Option C: Water - Water can act as a solvent in many reactions, affecting the rate of reaction. However, it does not directly reduce the activation energy of a chemical reaction.

Option D: Catalyst (Correct) - A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy without being consumed in the reaction. It provides an alternative reaction pathway with a lower activation energy, allowing the reaction to proceed more quickly. Therefore, a catalyst is the correct answer.

In summary, a catalyst is the substance that reduces the activation energy of a chemical reaction, allowing it to proceed more quickly without being consumed in the process.