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CBSE 12th Standard Chemistry Subject HOT Questions 1 Mark Questions With Solution 2021

Published on: 28/05/2021

QB365 Provides the HOT Question Papers for Class 12 Chemistry, and also provide the detail solution for each and every HOT Questions. HOT Questions will help to get more idea about question pattern in every exams and also will help to get more marks in Exams

Download CBSE Class 12th Standard CBSE Chemistry question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 12th Standard CBSE Chemistry

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Std: 12th Standard CBSE - Chemistry

chapter: - HOT Questions

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Questions:

Generic 2

4 x 2 = 8

For a second order reaction 2A ⟶ Product, a plot t_1/2 vs log a (a = initial conc.), what does the intercept represent?

Consider the reaction 2A + B ⟶ Products. When concentration of B alone was doubled, half life time does not change. When conc. of A alone doubled, the rate increases by two times . What are the units of K and what is the order of reaction?

What is the ratio of t_3/4 : t_1/2 for a first order reaction ?

How is half-life period related to initial concentration for a second order reaction ?

1 Marks

4 x 1 = 4

Can Mg reduce Al₂O₃ and Al reduces MgO? State the conditions required for this reduction process.

During metallurgical process, in the extraction of metal, flux is added. Why?

Which Substance is added to molten iron to remove sulphur impurity?

What are the oxidation states of iron in Fe₃O₄?

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Answers Key:

Generic 2

4 x 2 = 8

t_1/2 = 1/k .1/[Ao]
log t_1/2 = -log K – log [Ao]
Intercept = t_1/2.

The half life is independent of conc. of B. This means the reaction is of first order w.r.t. B and w.r.t. A also it is first order and overall order is second.

2:1

t_1/2 ∝a1−n.
For n = 2, t_1/2 ∝a−1,i.e.,
t_1/2 ∝ 1a
Thus, half-life period of a order reaction is inversely proportional to the initial concentration of the reactant.

1 Marks

4 x 1 = 4

()
If we look at the Ellingham diagram, it becomes evident that the plots for Al and Mg cross each other at 1350^∘C1350^∘C (1623 K). Below this temperature, Mg can reduce Al₂O₃Al₂O₃ and above this temperature, Al can reduce MgO.

()
Flux in the smelting process is added to, decrease the solubility of impurities, increase the fusion temperature of roasted ore and convert impurities into slag.
Flux removes the gangue to form easily fusible slag.
\(\mathrm{SiO}_{2}+\ \ \ \mathrm{FeO} \rightarrow\ \ \ \mathrm{FeSiO}_{3}\)
Acidicflux Basicangue Slag

()
To satisfy low sulfur requirements for iron processed into steel, magnesium reagents in powder or granular form are used to remove sulfur via slag-liquid metal reactions done under reducing conditions, where sulfur is transferred out of the steel through the slag-metal interface, and into the slag.