## NCERT 12 Physics Ray Optics And Optical Instruments Chapter 9 Exercise

Q.1. A small candle 2.5 cm in size is placed 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance form the mirror should a screen be placed in order of receive a sharp image ? Describe the nature and size of the image. If the candle is […]

## NCERT 12 Maths Matrices Chapter 3 – Exercise 3.2

Note: If two matrices have different orders then we can neither add nor subtract the matrices but we can multiply the matrices either the orders are same or number of columns of first matrix is equal to the number of rows of second matrix. By definition of equality of matrix as the given matrices are […]

## NCERT 12 Maths Relations and Functions Chapter 1 – Exercise

NCERT Solutions for Class 12 Maths and Chapter Wise Solutions, NCERT 12 Maths Relations and Functions Chapter 1 – Exercise. Relations and Functions Q 1. Determine whether each of the following relations are reflexive, symmetric and transitive: Relation R in the set A = {1,2,3, ….., 13, 14} defined as R = {(x, y): 3x-y=0} […]

## Biology 12 Biotechnology and Its Applications – Chapter 12 Exercise

Q 1. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because – Bacteria are resistant to the toxin Toxin is immature Toxin is inactive Bacteria encloses toxin in a special sac. Ans 1. Toxin is inactive. Q 2. What are transgenic bacteria? Illustrate using any one example. Ans 2. […]

## Biology 12 Human Health and Disease Chapter 8 – Exercise

Q 1. What are the various health measures which you would suggest to safeguard us against infectious diseases? Ans 1. Preventive measures are precautionary steps taken to check the transmission of infectious diseases. Common preventive measures include education, isolation, vaccination, sanitation, and sterilization. Education: People should be educated about the communicable diseases so that they […]

## NCRET 12 Physics Magnetism And Moving Charges chapter 4 Exercise

Q.1. A circular coil of wire consisting of 100 turns, each of radius 8.0 cm carries a current of 0.40 A. What is the magnitude of the magnetic field  at the centre of the coil? Q.2.A long straight wire carries a current of 35 A. What is the magnitude of the field at a point […]

## Biology 11 Biotechnology Principles and Processes Chapter 11 – Exercise

Q 1. Can you list 10 recombinants which are used in medical practice? Find where they are used as therapeutics (use internet). Ans 1. Some of the important recombinant proteins and their therapeutic uses are listed below: Recombinant proteins Therapeutic uses 1.     Insulin 2.     DNase I 3.     Tissue Plasminogen activator (t-PA) 4.     Anti-thrombin III 5.     […]

## Biology 12 Biodiversity and Conservation chapter 16 – Exercise

Biology 12 Biodiversity and Conservation chapter 16 – Exercise, Q 1. Name the three components of biodiversity. Ans 1. Three important components of biodiversity are: genetic diversity, species diversity and ecosystem diversity. Q 2. How do ecologists estimate the total numbers of species present in the world? Ans 2. Ecologists make a statistical comparison of […]

## NCERT 12 Physics Communication Chapter 15 Exercise

Q.1. Which of the following frequency/frequencies will be suitable for beyond the horizon communication using sky waves ? (a) 10 kHz (b) 10 MHz (c) 1 GHz (d) 1000 GHz Sol. Choice (b) is correct. This is because 10 kHz cannot be radiated due to large antenna size. 1 GHz and 1000 GHz will penetrate. […]

## NCERT 12 Physics Electromagnetic Waves Chapter 8 Exercise

Q.1. shows a capacitor made of two circular plates each of radius 12 cm and separated by 5.0 mm. The capacitor is being charged by an external source (not shown in the figure). The charging current is constant and equal to 0.15 A. (a) Calculate the capacitance and the rate of change of potential difference […]

## NCERT 12 Physics Nuclei Chapter 13 Exercise

Q.1.(a) Two stable isotopes of 3Li6 and 3Li7 have respective abundances of 7.5  and 92.5 . These isotopes have masses 6.01512 u and 7.01600 u respectively. Find the atomic weight of lithium.(b) Boron has two stable isotopes 5B10. Their respective masses are 10.01294 u and 11.00931 u, and the atomic weight of boron is 10.811 […]

## NCERT 12 Maths Matrices Chapter 3 – Exercise 3.1

Sol. (i) In the given matrix, the number of rows is 3 and the number of columns is 4. Therefore, the order of the matrix is 3 × 4. (ii) Since, the order of the matrix is 3 × 4, so there are 3 × 4 = 12 elements in it. 2. If the matrix […]

## Biology 12 Organism and Populations Chapter 13 – Exercise

Biology 12 Organism and Populations Chapter 13 – Exercise, Q 1. How is diapause different from hibernation? Ans 1. Hibernation is the phenomenon commonly depicted by ecothermal (cold-blooded) animals which escape cold by hiding them in shelters such as caves, burrows, cervices, hollow thee trunks, mud etc. revealing minimum physiological activity. This phenomenon is also […]

## chemistry 12 solution chapter 2 exercise 1

CHEMISTRY (CHAPTAR 2) NCERT EXERCISES WITH ANSWERS EX 2.1 Q – 2.1 Calculate the mass percentage of benzene (C6H6) and carbon tetrachloride (CCI4) is 22 g of benzene is dissolved in 122 g of carbon tetrachloride. Ans. Mass of solution = Mass of benzene + Mass of carbon tetrachloride = 22 g + 122g = […]

## Biology Molecular Basis of Inheritance Chapter 6 – Exercise

Q.1 Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. Ans. Nitrogenous bases: Adenine, Thymine, Uracil, Cytosine Nucleosides: Cytidine, Guanosine Q.2 If a double stranded DNA has 20% of cytosines, calculate the percent of adenine in the DNA. Ans. In a DNA molecule, the number of cytosine molecules is equal to […]

## NCERT 12 Chemistry Chemical Kinetics Chapter 4 Exercise 2

Q – 4.1. From the rate expressions for the following reactions, determine their order of reaction and the dimensions of the rate constants: 3 NO (g) ⟶ N2O (g) + NO2 (g) ; Rate = k [NO]2 H2O2 (aq) + 3 I- (aq) + H+ ⟶ 2 H2O (I) + I-3 ; Rate = k […]

## NCERT 12 Physics Current Electricity Chapter – 3 Exercises

Q.1. The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is 0. 4 Ώ, What is the maximum current that can be drawn from the battery ? Q.2. A battery of emf 10 V and internal resistance 3 Ώ is connected to a resistor. If […]

## NCERT 12 Chemistry General Principles and Processes Of Isolation of Elements Chapter 6 Exercise 1

Q.6.1. Suggest a condition under which magnesium could reduce alumina. Ans. The two redox reactions are : Q.6.2. Although thermodynamically feasible, in practice, magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium. Why? Ans. Below the temperature (1623 K), corresponding to the point of intersection of Al2 O3 and […]

## NCERT Maths 12 Solutions of Relations and Functions – Chapter 1 Ex 1.2

Q 1. Show that the function f : R* → R* defined by f(x) = 1/x is one-one, where R* is the set of all non-zero real numbers. Is the result true, if the domain R* is replaced by N with co-domain being same as R*? Sol. It is given that f : R* → R* is defined by f(x) = […]

## NCERT 12 Physics Semiconductor Electronics Materials, Devices And Simple Circuits Chapter 14 Exercise

Q.1. In n- type which of the following statement is true: (a) Electrons are majority carriers and trivalent atoms are the dopants (b) Electrons are minority carriers and pentavalent atoms are the dopants (c) Holes are minority carriers and pentavalent atoms are the dopants (d) Holes are majority carries and trivalent atoms are the dopants […]

## Biology 12 NCERT Ecosystem Solutions – Chapter 14 Exercise

Q 1. Fill in the blanks: Plants are called as ______ because they fix carbon dioxide. In an ecosystem dominated by trees, the pyramid (of numbers) is ______ type. In aquatic ecosystems, the limiting factor for the productivity is ______. Common detritivores in our ecosystem are ______. The major reservoir of carbon on earth is […]

## Biology Reproduction in Organisms Chapter 1 – Exercise

Q-1  Why is reproduction essential for organisms? Ans. Reproduction is essential for organisms because the continuity of the species generation after generation. Q-2 Which is a better mode of reproduction sexual or asexual ? Why ? Ans. Sexual reproduction is a better mode of reproduction because is needs meiosis and fusion of male and female […]

## NCERT 12 Physics Atoms Chapter 12 Exercise

Q.1. Choose the current alternative from the clues given at the end of each statement : (a) The size of the atom in Thomson’s model is ……. The atomic size in Rutherford’s modal (much greater than/no different from/much less than) (b) IN the ground state of………., electrons are in stable equilibrium, while in …….. electrons […]

## Biology 12 Principles of Inheritance and Variation Chapter 5

Q.1. Mention the advantages of selecting pea plant for experiment by Mendel. Ans. Mendel selected pea plant because of the following special feature : Garden peas were found to differ in certain definite and easily detectable traits. The traits of each kind of pea plant were presented in generation after generation because the plants had […]