Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Chemistry

Explain any two chemical methods of food preservation.

Give reasons  Acetylation of aniline reduces its activation effect.

Among the following, which one acts as a food preservative?

Aspartame, Aspirin, Sodium Benzoate, Paracetamol

Write the hybridisation and number of unpaired electrons in the complex `[CoF_6]^(3-)`. (Atomic No. of Co = 27)

Give reasons:

On the basis of E° values, O₂ gas should be liberated at anode but it is Cl₂ gas which is liberated in the electrolysis of aqueous NaCl.

Give reasons:

Conductivity of CH₃COOH decreases on dilution.

Give a simple chemical test to distinguish between Aniline and N, N-dimethylaniline

Seeing the growing cases of diabetes and depression among children, Mr. Chopra, the principal of one reputed school organized a seminar in which he invited parents and principals. They all resolved this issue by strictly banning the junk food in schools and by introducing healthy snacks and drinks like soup, lassi, milk etc. in school canteens. They also decided to make compulsory half an hour physical activities for the students in the morning assembly daily. After six months, Mr. Chopra conducted the health survey in most of the schools and discovered a tremendous improvement in the health of students.

After reading the above passage, answer the following questions :

(i) What are the values (at least two) displayed by Mr. Chopra ?

(ii) As a student, how can you spread awareness about this issue ?

(iii) Why should antidepressant drugs not be taken without consulting a doctor ?

(iv) Give two examples of artificial sweeteners.

Complete and balance the following equation: 

\[\ce{PCl3 + H2O ->}\] 

Write one example each of Artificial sweetener.

Write one example each of Antacids.

[NiCl₄]^2- is paramagnetic while [Ni(CO)₄] is  diamagnetic though both are tetrahedral. Why? (Atomic no. Ni = 28) 

 Why is alpha (α) hydrogen of carbonyl compounds acidic in nature?

For a reaction
\[\ce{2H2O2->[I^-][Alkaline medium]2H2O + O2}\]

The Proposed mechanism is given below: 
(1) H₂O₂+I^- → H₂O+IO^-(slow)
(2) H₂O₂+IO^-→H₂O+I^-+O₂(fast)

(i) Write the rate law for the reaction.
(ii) Write the overall order of a reaction.
(iii) Out of steps(1) and (2), which one is the rate-determining step? 

Write chemical reactions taking place in the extraction of copper from Cu₂ S. 

Is   a homopolymer or copolymer? Give reason. 

Why the use of alitame as an artificial sweetener is not recommended? 

Write chemical equations of the following reaction : 

Propanone is treated with dilute Ba (OH)_2-.

Write chemical equations of the following reaction :
Benzoyl chloride is hydrogenated in the presence of `"Pd"/(BaSO_4)`

Write a chemical equation for the following reaction: 
Propanone is treated with dilute Ba( OH)₂.