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

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have the highest bond dissociation enthalpy?

On heating compound (A) gives a gas (B) which is a constituent of air. This gas when treated with 3 mol of hydrogen (H₂) in the presence of a catalyst gives another gas (C) which is basic in nature. Gas C on further oxidation in moist condition gives a compound (D) which is a part of acid rain. Identify compounds (A) to (D) and also give necessary equations of all the steps involved.

Read the passage carefully and answer the questions that follow:

Answer the following questions:

1. A segment of DNA has 100 adenine and 150 cytosine bases. What is the total number of nucleotides present in this segment of DNA?
2. A sample of hair and blood was found at two sites. Scientists claim that the samples belong to same species. How did the scientists arrive at this conclusion?
3. The sample of a virus was tested and it was found to contain 20% adenine, 20% thymine, 20% guanine and the rest cytosine. Is the genetic material of this virus (a) DNA-double helix (b) DNA-single helix (c) RNA? What do you infer from this data?
   OR
   How can Chargaff’s rule be used to infer that the genetic material of an organism is double-helix or single-helix?

Write the main product in the following reaction:

DNA fingerprinting is used to determine paternity of an individual. Which property of DNA helps in the procedure?

Account for the following:

Fluorine forms only one oxoacid HOF.

Draw the structures of the following:
(1) HClO₄
(2) H₃PO₃

When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA?

Draw the structures of the HClO₃.

Account for the following :

HClO₄ is a stronger acid than HClO.

The increasing order of reducing power of the halogen acids is:

Which of the following statements is true for protein synthesis?

Which one of the following order is correct for the bond dissociation enthalpy of halogen molecule?

Assertion: HI cannot be prepared by the reaction of KI with concentrated H₂SO₄.

Reason: HI has the lowest H-X bond strength among halogen acids.

A black compound of manganese reacts with a halogen acid to give greenish-yellow gas. When excess of this gas reacts with \[\ce{NH3}\] an unstable trihalide is formed. In this process the oxidation state of nitrogen changes from ______.

Explain why the stability of oxoacids of chlorine increases in the order given below:

\[\ce{HClO < HClO2 < HClO3 < HClO4}\]

Assertion: \[\ce{HI}\] cannot be prepared by the reaction of KI with concentrated \[\ce{H2SO4}\]

Reason: \[\ce{HI}\] has lowest \[\ce{H - X}\] bond strength among halogen acids.

Draw the structures of the following molecules: BrF₃

ICl is more reactive than I₂.

Account for the following: Interhalogens are more reactive than pure halogens.