Pragya tested the solubility of three different substances at different temperatures and collected, the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution). To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find its concentration at this temperature. What is saturated solution? Question 2. (b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride. Which postulate of Dalton’s atomic theory can explain the law of definite proportions? What is the principle for separation of immiscible liquids? Why is crystallisation better than evaporation? What do you understand by a Saturated solution? NCERT Solutions Class 9 Science Chapter 2 Is Matter Around Us Pure – Here are all the NCERT solutions for Class 9 Science Chapter 2. Mass of solution = Mass of solute + Mass of solvent Add requisite sugar which dissolves and the tea is ready. Pure Substance: A pure substance consists of a single of matter or particles and cannot be separated into other kind of matter by any physical process. The particles of a suspension can be seen by naked eyes. Calculate the formula unit masses of ZnO, Na2O, K2CO3, given atomic masses of Zn = 65u, The formula unit mass of ZnO= Atomic mass of Zn + Atomic mass of O = 65u+16u = 81u, The formula unit mass of Na2O = 2 x Atomic mass of Na + Atomic mass of O = (2 x 23)u +16u=46u+16u=62u. If the given colourless liquid boils exactly at 373 K at 1 atmospheric pressure, then it is pure water. 5. What is “solubility” of a solute? Define solute. He also uses unleaded petrol and makes use of public transport wherever possible. (a) What is the principle of using and working of separating funnel? The postulate of Dalton’s atomic theory that can explain the law of definite proportions is – the (a) What is aerosol? Question 18. Question 13. The molecular mass of H2 – 2 x atoms atomic mass of H = 2 x 1u = 2u, The molecular mass of O2 – 2 x atoms atomic mass of O = 2 x 16u = 32u, The molecular mass of Cl2 – 2 x atoms atomic mass of Cl = 2 x 35.5u = 71u, The molecular mass of CO2 – atomic mass of C + 2 x atomic mass of O = 12 + ( 2×16)u = 44u, The molecular mass of CH4 – atomic mass of C + 4 x atomic mass of H = 12 + ( 4 x 1)u = 16u, The molecular mass of C2H6– 2 x atomic mass of C + 6 x atomic mass of H = (2 x 12) +, The molecular mass of C2H4– 2 x atomic mass of C + 4 x atomic mass of H = (2x 12) +, The molecular mass of NH3– atomic mass of N + 3 x atomic mass of H = (14 +3 x 1)u= 17u, The molecular mass of CH3OH – atomic mass of C + 3x atomic mass of H + atomic mass of O + atomic mass of H = (12 + 3×1+16+1)u=(12+3+17)u = 32u. (c) Mass of 1 mole of sodium sulphite Na2SO3 = Molecular mass of sodium sulphite = 2 x Mass of Na + Mass of S + 3 x Mass of O = (2 x 23) + 32 +(3x 16) = 46+32+48 = 126g, Therefore, mass of 10 moles of Na2SO3 = 10 x 126 = 1260g, This is very useful thank you so much , Your email address will not be published. If you are a student of class 9 who is using NCERT Textbook to study Science, then you must come across Chapter 2 Is Matter Around Us Pure. (g) Tea leaves from tea. Question 2: Explain how does soap help in cleaning dirty clothes? What is the difference in fog and smoke? E.g., gold, silver. 7. Heat it. The ratio of oxygen: hydrogen combination is always constant i.e., 1: 2 by volume. Rita’s father always got his vehicle checked for pollution control. (b) Different types of solution: Answer: The properties of both naphthalene and common salt should be known, before we choose the separation technique. Distinguish between a physical change and chemical change. While buying a bottle he felt that it was slightly heavier than usual deodorant bottle that he purchased everytime. NCERT Solutions for Class 9 Science Chapter 6 Short Answer Type Questions. Here you can get complete NCERT Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure in one place. Two or more atoms tightly bound together form a molecule. The NCERT Class 9 Science solutions are provided with detailed and precise answers to help you solve exercise questions with better understanding. Question 10. Colloidal solution show Tyndall effect but true solution do not. If one mole of carbon atoms weighs 12grams, what is the mass (in grams) of 1 atom of carbon? Question 4. Question 3: How will you justify that rusting of iron is a chemical change? (c) Rita’s father is an aware citizen, environmentally concerned and dutiful. Question 6. (b) Apart from water what is the other substance that some shopkeepers add into the deodorant. If 20g of salt is present is 220 g of solution, calculate the concentration of solution: Question 1. (d) Suspension Which has more number of atoms, 100 grams of sodium or 100 grams of iron (given, atomic mass of Na = 23u, Fe = 56 u)? Question 8. An inverted funnel is kept over the mixture in China dish with plugged stem. (i) butter from curd, Choose the correct option: It remains in the vapours state. (a) salt solution (b) sugar solution It is because the solute particle has taken all the inter molecular space present in the solvent. (b) 4 moles of aluminium atoms((Atomic mass of aluminium =27)? Heterogeneous: Wood, air, soil. The components do not have any fixed proportion. A 0.24g sample of compound of oxygen and boron was found by analysis to contain 0.096g of boron and 0.144g of oxygen. Download Class 9 Science App for offline use. Answer: Question 3. Question 15. Answer: Mass of solute (sodium chloride) = 36 g Give one example of gas in liquid solution. The scattering of light by colloidal particles is known as Tyndall effect. (g) Gases from air (h) Petrol and diesel from crude oil He need to separate this mixture. Classify the following as chemical or physical changes: Question 3. How can you separate the following mixtures? How will you separate a mixture of oil and water? Question 1. Answer 3: The rust is a brown chemical compound known as hydrated ferric oxide. Why water is called universal solvent? (i) Based on solvent—Aqueous and non-aqueous Aqueous solution has water as solvent (sugar + water) Non-aqueous solution has some other solvent but not water. 50 gm sugar is dissolved in a glass of water at 30°C. When the solid or liquid is dispersed in a gas it is called aerosol. 1.