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

When chlorine reacts with a cold and dilute solution of sodium hydroxide, it forms:

The cell membranes are mainly composed of:

The correct order of bond angles in the following species is:

When Cl₂ reacts with hot and conc. NaOH, the oxidation number of chlorine changes from ____________.

Chlorine reacts with excess of NH₃ to form:

Assertion: \[\ce{NaCl}\] reacts with concentrated \[\ce{H2SO4}\] to give colourless fumes with pungent smell. But on adding \[\ce{MnO2}\] the fumes become greenish yellow.

Reason: \[\ce{MnO2}\] oxidises \[\ce{HCl}\] to chlorine gas which is greenish yellow.

Chlorine water loses its yellow colour on standing because ______.

Convert the following:

Propan-1-ol to 2-Bromopropanoic acid

Assertion (A): Acetic acid but not formic acid, can be halogenated in the presence of red P and Cl₂.

Reason (R): Acetic acid is a weaker acid than formic acid.

What is the difference between a nucleoside and nucleotide?

The two strands in DNA are not identical but are complementary. Explain.

What is the difference between Nucleotide and Nucleoside? 

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

The correct order of acid strength of oxyacids is:

The nucleic acid base having two possible binding sites is ____________.

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.

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?