HSC Science (Electronics) इयत्ता १२ वी - Maharashtra State Board Important Questions

What is the role of the following compound- 
SiO₂ in the extraction of copper from copper pyrites?

In a first-order reaction A → product, 80% of the given sample of compound decomposes in 40 min. What is the half-life period of the reaction? 

Answer the following in one or two sentences.

What is the relationship between coefficients of reactants in a balanced equation for an overall reaction and exponents in the rate law? In what case the coefficients are the exponents?

Answer the following in one or two sentences.

Why all collisions between reactant molecules do not lead to a chemical reaction?

Answer the following in brief.

How instantaneous rate of reaction is determined?

A reaction takes place in two steps:

1. \[\ce{NO_{(g)} + Cl2_{(g)} -> NOCl2_{(g)}}\]
2. \[\ce{NOCl2_{(g)} + NO_{(g)} -> 2NOCl_{(g)}}\]

1. Write the overall reaction.
2. Identify the reaction intermediate.
3. What is the molecularity of each step?

Answer the following in brief.

Obtain the relationship between the rate constant and half-life of a first-order reaction.

What are pseudo-first-order reactions?

Answer the following in brief.

Explain graphically the effect of temperature on the rate of reaction.

Solve

The half-life of a first-order reaction is 1.7 hours. How long will it take for 20% of the reactant to react?

Show that the time required for 99.9% completion of a first-order reaction is three times the time required for 90% completion.

How will you determine activation energy from rate constants at two different temperatures?

Answer the following in brief.

Give one example and explain why it is pseudo-first-order.

The rate law relates to the rate of a chemical reaction in terms of _______.

For first order reaction, the rate constant for the decomposition of N₂O₅ is 6 × 10^–4 s ^–1. The half-life period for decomposition in seconds is ______.

Effect of catalyst in a chemical reaction is to change the _______.

Give one example of a pseudo first-order reaction.

Explain pseudo first order reaction with a suitable example.

Explain with the help of a potential energy diagram that the catalyst increases the rate of the reaction.

Why is molecularity applicable for only elementary reactions whereas order of a reaction is applicable for elementary and complex reactions? Explain with suitable examples.