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

Which of the following is isoelectronic pair?

Which of the following statements are true?

(i) Only type of interactions between particles of noble gases are due to weak dispersion forces.

(ii) Ionisation enthalpy of molecular oxygen is very close to that of xenon.

(iii) Hydrolysis of XeF₆ is a redox reaction.

(iv) Xenon fluorides are not reactive.

Give reason to explain why ClF₃ exists but FCl₃ does not exist.

A hydrocarbon ‘A’, \[\ce{(C4H8)}\] on reaction with \[\ce{HCl}\] gives a compound ‘B’, \[\ce{(C4H9Cl)}\], which on reaction with 1 mol of \[\ce{NH3}\] gives compound ‘C’, \[\ce{(C4H11N)}\]. On reacting with \[\ce{NaNO2}\] and \[\ce{HCl}\] followed by treatment with water, compound ‘C’ yields an optically active alcohol, ‘D’. Ozonolysis of ‘A’ gives 2 mols of acetaldehyde. Identify compounds ‘A’ to ‘D’. Explain the reactions involved.

Which of the following B group vitamins can be stored in our body?

Why must vitamin C be supplied regularly in diet?

Match the vitamins given in Column I with the deficiency disease they cause given in Column II.

Assertion: Vitamin D can be stored in our body.

Reason: Vitamin D is fat-soluble vitamin.

Which one of the following would feel attraction when placed in magnetic field: Co²⁺, Ag⁺, Ti⁴⁺, Zn²⁺ 

Given below are two statements labelled as Assertion (A) and Reason (R).

Assertion: Magnetic moment values of actinides are lesser than the theoretically predicted values.

Reason: Actinide elements are strongly paramagnetic.

Select the most appropriate answer from the options given below:

Write the equations for the following reaction:

Salicylic acid is treated with acetic anhydride in the presence of conc H₂SO₄

Give a reason for the following observations:

Water soluble vitamins must be taken regularly in the diet.

Assertion (A): Vitamin C cannot be stored in our body.

Reason (R): Vitamin C is fat soluble and is excreted from the body in urine.

The vitamins which can be stored in our body are ______.

What are three types of RNA molecules which perform different functions?

What type of linkage is present in nucleic acids?

Predict the products of the following reactions :

Define the following term: 

Nucleotide

In terms of band theory, what is the difference between a conductor and an insulator?

In terms of band theory, what is the difference between a conductor and a semiconductor?