NCERT Solutions for Class 11 Maths Exercise 7.1 Permutations and Combinations

Ellipse: Do you know the orbit of planets, moon, comets, and other heavenly bodies are elliptical? Mathematics defines an ellipse as a plane curve surrounding...

Altitude of a triangle is the side that is perpendicular to the base. A triangle has three sides altitude, base and hypotenuse. The altitude of...

Manufacturing of Sulphuric Acid by Contact Process: Sulphuric acid is referred to as the king of chemicals. It is one of the most important chemical...

Refining or Purification of Impure Metals: Metals like Copper, Aluminium, Iron, etc., occur in nature in the combined state, in the form of their oxides,...

Pollination and Outbreeding Devices: Flowers are symbolic of beauty and have aesthetic, ornamental, social, religious and cultural value. But how are they formed? Let us...

Electrochemical Principles of Metallurgy: Electrochemistry is a branch of chemistry that is concerned with the relation between electric current and chemical reactions. The processes involved...

Acid rain isn't pure acid falling from the sky; rather, rainfall or atmospheric moisture mixed with elements and gases cause the moisture to become more...

Congruence of Triangles: The congruence of a triangle depends upon the measurements of sides and angles of the two triangles. There are a few criteria,...

Complementary and Supplementary angles are defined for the addition of two angles. If the sum of two angles so formed is \({90^ \circ }\), then...

Nitro compounds are a group of organic compounds having Nitro group \({\rm{( - O - N = O)}}\) as a part of its molecular structure....

Bond Linking Monomers in Polymers: Every living thing is made up of various proteins, enzymes, certain peptide hormones, carbohydrates, nucleic acids, polyphenolics etc. are important...

Higher animals possess an elaborated circulatory system that consists of a muscular and chambered heart, a network of blood vessels, and an extracellular fluid called...

Applications of Equilibrium Constant: The numerical value of the equilibrium constant is critical because it tells us whether we should expect a reaction mixture at...

Machines: Do you know we can easily lift heavy loads with a small effort? Do you know we can make the work easier with the...

Algebra of Complex Numbers: Complex numbers have wide applications in various fields of science, such as AC circuit analysis. Learning about the algebra of complex numbers...

The Lanthanoids: How many elements do you think there are in and around us? They can be counted, however counting them on your fingers is...

Important Trends and Anomalous Behaviour of Carbon: You know how important carbon is for our existence. Even our bodies are largely composed of carbon compounds....

Preparation of Colloidal Solutions: As we know, all solutions contain two entities in them, a solvent and a solute, mixed together to form a solution....

Deliquescence: We all must have seen tiny silica gel packets inside shoe boxes, new bags, and other gadgets, and they are there for a reason....

Periodic Trends in the Properties of Elements: The long form of the periodic table or the modern periodic table can also be called Bohr’s table...

Occurrence of Group 17 Elements: On the periodic table, the halogens are to the left of the noble gases. Fluorine \(\left( {\rm{F}} \right){\rm{,}}\) chlorine \(\left(...

Dinitrogen: Nitrogen is a colourless, odourless, and tasteless element that is plentiful in nature. Daniel Rutherford, a Scottish physician, was the first to discover it...

Drug-Target Interaction: As we've seen, chemistry plays a crucial role in practically every aspect of our lives. Medicinal chemistry is one such topic that is...

Biotechnology: The application of engineering science principles and technological methods on biological systems, like microorganisms, higher animals, and plants, intending to carry out chemical, environmental...

Health Organisations: Did you know that ischemic heart disease is the leading cause of disease worldwide? Last year heart disease killed \(4.77\) million people in...

Neural and Hormonal Control of Digestion: Taste and smell are related. What happens when we walk past a fast-food stall and catch a whiff of...

Towards Quantum Mechanical Model of the Atom: Bohr is widely credited with developing the first quantitatively successful model of the atom. However, the newer Wave...