Author: Dr. Vikas Jasrotia

Periodic Classification of Elements Questions PDF (Answers) Periodic Classification of Elements Questions PDF Ans 1. NaOH > Mg(OH)2 > Al(OH)3. Because the basic strength decreases in a period on moving from left to right. Ans 2. 2, 8, 6 is the electronic configuration of the element with atomic number 16. It has 6 valence electrons. It belongs to the 16th group and the 3rd period. Ans 3. (i) Na, Si, and Cl have different properties, therefore they do not form Dobereiner’s triads even though the atomic mass of the middle atom Si (At. Mass – 28) is approximately the average…

Periodic Classification of Elements Questions Periodic Classification of Elements Questions Que 1. What is the correct order of relative basic character of NaOH, Mg(OH)2, and Al(OH)3? Que 2. An element has the atomic number 16. To which group and period does it belong? Que 3. Can the following groups of elements be classified as Dobereiner’s triad? i) Na, Si, Cl ii) Be, Mg, Ca Atomic mass of Be – 9, Na – 23, Mg – 24, Si – 28, Cl – 35, Ca – 40. Give justification for your Answer. Que 4. What was the basis of the classification of elements…

Carbon and Its Compounds Class 10 Solutions of Practice Questions Carbon and Its Compounds Class 10 Solutions Ans 1. (i) CH3Cl Chloromethane (ii) C2H5Cl Chloroethane Ans 2. Covalent compounds have low melting and boiling points due to small intermolecular forces of attraction between the atoms. Ans 3. (i) Alcohol group (ii) Carboxylic acid group Ans 4. Unsaturated hydrocarbons have more amount of carbon, therefore burn with smoky flame due to incomplete combustion. Ans 5. (i) Valency of each carbon atom in an alkane is four. (ii) Valency of each carbon atom in an alkyne is four. Ans 6. (i) Catenation…

Carbon and Its Compounds Class 10 Practice Questions Carbon and Its Compounds Class 10 Practice Questions Que 1. Write the molecular formula of the first two members of the homologous series having a functional group — Cl. Que 2. Why covalent compounds are volatile in nature with low boiling and low melting point? Que 3. Give the names of the following functional groups: (i) — OH (ii) — COOH Que 4. Unsaturated hydrocarbon gives a yellow flame with a lot of black smoke when burnt in oxygen. Give reason. Que 5. State the valency of each carbon atom in (i)…

Metals and Non-Metals Class 10 Important Questions (Worksheet Answers) metals and non metals class 10 important questions with answers Ans 1. Calcium form hydrogen gas in reaction with water, bubbles of hydrogen gas stick to the calcium metal and that is why calcium floats in water. Ca(s) + 2H2O(l) → Ca(OH)2 (aq) + H2 (g) Ans 2. (a) Carbon makes it hard and strong. Tungsten also makes it hard and strong. (b) Mercury is alloyed with metals to form an amalgam. (c) Zinc metal is used for coating over iron metal to galvanise iron. (d) Silver articles acquire black coating…

Metals and Non Metals Class 10 Important Questions (Worksheet) Metals and Non Metals Class 10 Important Questions Que 1. Why does calcium float in water? Que 2. Name a metal/non-metal (a) Which makes iron hard and strong? (b) Which is alloyed with other metals to make amalgam? (c) Which is used to galvanise iron articles? (d) Whose articles when exposed to air form a black coating? Que 3. Why is sodium chloride soluble in water but not in kerosene? Que 4. A copper plate was dipped into a solution of silver nitrate. After some time a black layer was observed…

Questions on Acids Bases and Salts Class 10 (Answers) Questions on Acids Bases and Salts Class 10 (Answers) Ans 1. Curd contains lactic acid which can make poisonous compounds with brass and copper vessels. Ans 2. The fizzing will occur more vigorously in test tube ‘A’ because HCl is a strong acid and reacts faster than acetic acid which is a weak acid. Ans 3. (a) Highly soluble bases are called alkalies e.g., KOH. (b) Bee sting contains HCOOH, formic acid which causes irritation. Baking soda (basic) neutralises HCOOH, therefore it gives relief from pain by rubbing it on the…

Questions on Acids Bases and Salts Class 10 Questions on Acids Bases and Salts Class 10 Que 1. Curd is not kept in copper and brass utensils, why? Que 2. Equal lengths of magnesium ribbon are taken in test tubes ‘A’ and ‘B’. Hydrochloric acid (HCl) is added to test tube A’ while acetic acid (CH3COOH) is added to test tube ‘B’. In which test tube, will fizzing occur more vigorously and why? Que 3. (a) Write the name given to the bases that are highly soluble in water. Give an example. (b) Why does a bee sting cause pain…

Is Matter Around Us Pure Class 9 (Practice – 1 Answer) Is Matter Around Us Pure Class 9 Ans 1. The net movement of molecules from a region of high concentration to one of lower concentration. A spray of perfume or room freshener will get diffused into the air by which we can sense the odour. Ans 2. The matter has three states i.e Solid, Liquid, and Gases. Ans 3. The smell of hot sizzling food reaches you several meters away, but to get the smell of cold food, we have to go close because the kinetic energy of particles…

Is Matter Around Us Pure Questions (Practice) Que 1. Define diffusion with an example. Que 2. How many states of matter are there? Que 3. Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away, but to get the smell of cold food, you have to go close. Que 4. Comment on the following statements: (a) Evaporation causes cooling. (b) Rate of evaporation of an aqueous solution decreases with an increase in humidity. (c) Sponge though compressible is solid. (d) Ice is solid at 0°C, while water is liquid at room temperature. (e)…