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Chapter – 4 Chemical Bonding And Molecular Structure 1. Explain the formation of a chemical bond. Solution : A chemical bond is defined as an attractive force that holds the constituents (atoms, ions etc.) together in a chemical species.Various theories have been suggested for the formation of chemical bonds such as the electronic theory, valence … Read more
Chapter – 3 Classification of Elements and Periodicity in Properties 1. Explain why the electron gain enthalpy of fluorine is less negative than that of chlorine. Answer. This is due to the small size of the fluorine atom. As a result of the strong inter electronic repulsions in fluorine’s relatively small 2 p orbitals, the … Read more
Chapter – 4 Laws of Motion 1. Give the magnitude and direction of the net force acting on (a) a drop of rain falling down with a constant speed (b) a cork of mass 10 g floating on water (c) a kite skillfully held stationary in the sky (d) a car moving with a constant … Read more
Chapter – 3 Motion in a plane Q-1: State whether the following physical quantities are scalar or vector. (i) Mass (ii) Volume (iii) Speed (iv) Acceleration (v) Density (vi) Number of moles (vii) Velocity (viii) Angular frequency (ix) Displacement (x) Angular velocity Ans: Scalar: Density, mass, speed, volume, angular frequency, number of moles.Vector: Velocity, acceleration, … Read more
Chapter – 2 Motion in a straight line Q 1. In which of the following examples of motion can the body be consider dapp rox ima tely a point object? (a) A railway carriage moving without jerks between two stations. (b) A cap on top of a man cycling smoothly on a circular track. (c) … Read more
Chapter – 1 Unit And Measurement 2.1 Fill in the blanks. (a) The volume of a cube of side 1 cm is equal to …..m3 (b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to…(mm)2 (c) A vehicle moving with a speed of 18 km h–1 … Read more
Chapter – 1 The Living world 1. Why are living organisms classified? Solution: The earth contains millions of organisms, and we may know the plants and animals that live near us by their native names. The local names vary from place to place within a country. This leads to confusion in identifying and studying specific … Read more
शरीर में पानी की कमी, जिसे निर्जलीकरण (dehydration) कहते हैं, कई स्वास्थ्य समस्याओं का कारण बन सकती है। संक्षेप में, पानी की कमी से निम्नलिखित प्रभाव हो सकते हैं: शारीरिक प्रदर्शन में कमी: मांसपेशियों की थकान और कमजोरी, जिससे शारीरिक प्रदर्शन घट जाता है।थकान और कमजोरी: ऊर्जा की कमी महसूस होना और आसानी से थक … Read more
Chapter 2 Structure of Atom 1. (i) Calculate the number of electrons which will together weigh one gram.(ii) Calculate the mass and charge of one mole of electrons. Solution : (i) Mass of one electron = 9.10939 × 10–31 kg Number of electrons that weigh 9.10939 × 10–31 kg = 1Number of electrons that will … Read more
Chapter 1 Some Basic Concepts of Chemistry 1. Calculate the molecular mass of the following : (i) H2O (ii) CO2 (iii) CH4 Solution : (i)CH4 :Molecular weight of methane, CH4= (1 x Atomic weight of carbon) + (4 x Atomic weight of hydrogen)= [1(12.011 u) +4 (1.008u)]= 12.011u + 4.032 u= 16.043 u (ii) H2O … Read more