Q4. What did the ancient atomic ideas of Kanada and Democritus lack, compared with Dalton’s atomic theory?
They were intuitive guesses that were not tested and improved by quantitative experiments. Dalton’s theory was built to explain measured laws of chemical combination, the laws of definite and multiple proportions.
Q5. Copper has a density of 8960 kg m and a molar mass of 0.0635 kg mol. Roughly how many atoms are there in a cube of copper 1 mm on a side?
Mass = 8960 × 10 kg. Moles = 8960 × 10/0.0635. Atoms = that × 6.02 × 10, about 8.5 × 10.
Q6. What is meant by saying that a gas in a closed container is in dynamic equilibrium?
Its molecules never stop moving and colliding, and each molecule’s speed keeps changing. But the average properties of the gas, such as its pressure and temperature, stay constant, so the gas as a whole is in equilibrium.