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Answer :

The postulate of Dalton’s Atomic theory which is a result of the law of conservation of mass is, “Atoms are indivisible particles, which can neither be created nor be destroyed”.

- In a reaction, 5.3g of sodium carbonate reacted with 6 g of acetic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium acetate. Show that these observations are in agreement with the law of conservation of mass. Sodium carbonate + acetic acid \(\rightarrow \) Sodium acetate + carbon dioxide + water
- Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?
- Which postulate of Dalton’s atomic theory can explain the law of definite proportions?
- Define the atomic mass unit?
- 2. Why is it not possible to see an atom with naked eyes?
- Write down the formulae of (i) sodium oxide (ii) aluminium chloride (iii) sodium sulphide (iv) magnesium hydroxide
- Write down the names of compounds represented by the following formulae: (i) Al\( _2 \)(SO\( _4 \))\( _3 \) (ii) CaCl\( _2 \) (iii) K\( _2 \)SO\( _4 \) (iv) KNO\( _3 \) (v) CaCO\( _3 \)
- What is meant by the term chemical formula?
- How many atoms are present in a (i) H\( _2 \)S molecule and (ii) PO\( _4 \)\(^{3-} \) ion?
- Calculate the molecular masses of H\( _2 \) , O\( _2 \) , Cl\( _2 \), CO\( _2 \), CH\( _4 \), C\( _2 \)H\( _6 \), C\( _2 \)H\( _4 \), NH\( _3 \), CH\( _3 \)OH.
- Calculate the formula unit masses of ZnO, Na\( _2 \)O, K\( _2 \)CO\( _3 \), given atomic masses of Zn = 65u, Na = 23 u, K=39u, C = 12u, and O=16u.
- If one mole of carbon atoms weighs 12grams, what is the mass (in grams) of 1 atom of carbon?
- Which has more number of atoms, 100 grams of sodium or 100 grams of iron (given, atomic mass of Na = 23u, Fe = 56 u)?

- NCERT solutions for class 9 maths chapter 1 Number Systems
- NCERT solutions for class 9 maths chapter 2 Polynomials
- NCERT solutions for class 9 maths chapter 3 Coordinate geometry
- NCERT solutions for class 9 maths chapter 4 Linear equations in two variables
- NCERT solutions for class 9 maths chapter 5 Introduction to Euclidean Geometry
- NCERT solutions for class 9 maths chapter 6 Lines and Angles
- NCERT solutions for class 9 maths chapter 7 Triangles
- NCERT solutions for class 9 maths chapter 8 Quadrilaterals
- NCERT solutions for class 9 maths chapter 9 Areas of parallelograms and triangles
- NCERT solutions for class 9 maths chapter 10 Circles
- NCERT solutions for class 9 maths chapter 11 Constructions
- NCERT solutions for class 9 maths chapter 12 Heron's Formula
- NCERT solutions for class 9 maths chapter 13 Surface areas and volumes
- NCERT solutions for class 9 maths chapter 14 Statistics
- NCERT solutions for class 9 maths chapter 15 Probability

- NCERT solutions for class 9 science chapter 1 Matter in our Surroundings
- NCERT solutions for class 9 science chapter 2 Is Matter Around Us Pure
- NCERT solutions for class 9 science chapter 3 Atoms and Molecules
- NCERT solutions for class 9 science chapter 4 Structure of the Atom
- NCERT solutions for class 9 science chapter 5 The Fundamental Unit of Life
- NCERT solutions for class 9 science chapter 6 Tissues and Fundamental unit of life
- NCERT solutions for class 9 science chapter 7 Diversity in Living Organisms
- NCERT solutions for class 9 science chapter 8 Motion
- NCERT solutions for class 9 science chapter 9 Force and Laws of Motion
- NCERT solutions for class 9 science chapter 10 Gravitation
- NCERT solutions for class 9 science chapter 11 Work and Energy
- NCERT solutions for class 9 science chapter 12 sound
- NCERT solutions for class 9 science chapter 13 Why do We Fall Ill
- NCERT solutions for class 9 science chapter 14 Natural Resources
- NCERT solutions for class 9 science chapter 15 Improvement in Food Resources