Science (English Medium) Class 12 - CBSE Question Bank Solutions

Chlorine water loses its yellow colour on standing because ______.

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?

The mixture of concentrated HCl and HNO₃ made in 3 : 1 ratio contains:

The correct order of acid strength of oxyacids is:

Which of the following statements is true for protein synthesis?

The correct order of acid strength is:

On addition to conc. \[\ce{H2SO4}\] to a chloride salt, colourless fumes are evolved but in the case of an iodide salt, violet flames come out. This is because ______.

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.

Account for the following:

Fluorine forms only one oxoacid HOF.

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

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 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