Matter-Nature and Behaviour (Conceptual Questions with Very Short Answers)
Question 1. How many elements are known at present?
Answer.
115.
Question 2. How many elements occur in nature?
Answer.
92.
Question 3. Give one example each of homogeneous and heterogeneous mixture.
Answer.
Homogeneous mixture – Iodized table salt. Heterogeneous mixture – milk.
Question 4. Name the apparatus by which mixture of oil and water can be separated.]
Answer.
Separating funnel.
Question 5. Name the gas which exists in liquid state at room temperature.
Answer.
Bromine.
Question 6. Name the metal which is liquid at room temperature.
Answer.
Mercury.
Question 7. Name two metals which are malleable as also ductile.
Answer.
Copper, Silver.
Question 8. How can we check whether the given solid substance is pure or not?
Answer.
By checking its melting point whether it agrees with the value given in tables or not, If it agrees then it is pure.
Question 9. A hard substance produces a tinkling sounds when beat. Is it metal or a non-metal?
Answer.
It is a metal. (Metals are hard and produce tinkling sound.)
Question 10. Why is diamond used as glass cutter?
Ans.
Diamonds is the hardest substance and for this property it is used as glass cutters.
Question 11. Is brass a mixture or a compound?
Answer.
It is mixture, because its composition is variable.
Question 12. In which range lies the size of colloidal particles?
Answer.
It lies in the range 1 nm to 100nm (1nm=10-9)
Question 13. If the path of light becomes visible on being passed through a solution, what type of solution is it?
Answer. It is a colloidal solution.
Question 14. When a colloidal solution of sulphur is centrifuged in a centrifugal machine, what will you observe?
Answer.
After some time yellow precipitate of sulphur will settle down at the bottom of the tube and the solution will become colourless.
Question 15. Mass percent is one of the methods of expressing the concentration of a solution. In this methods what are the units, of mass percent?
Answer.
It has no units. It is simply a ratio.
Question 16. Name the dispersed phase and dispersion medium in case of an emulsion.
Answer.
Dispersed phase – liquid Dispersion medium – liquid
Question 17. Name the dispersed phase and dispersion medium in case of dust-storm?
Answer.
Dispersed phase: solid (dust particles)Dispersion medium: gas (air)
Question 18. Give one example of a solution of gas in a liquid.
Answer.
Ammonia gas dissolved in water.
Question 19. Which type of emulsion is milk?
Answer.
Milk is oil-in-water type emulsion.
Question 20. What type of solution is an alloy? liquid solution or solid solution.
Answer.
Alloy is a solid solution.
Question 21. Do suspension show the property of Tyndall effect?
Answer.
Yes.
Question 22. Can we separate the components of a suspension by process of filtration?
Answer.
Yes.
Question 23. Name the type of dispersed phase and dispersion medium in haze.
Answer.
Dispersion medium,: gas Dispersed phase: solid
Question 24. What type of change is burning of candle?
Answer.
It is a chemical change.
Question 25. A mixture consisting of two miscible liquids ‘A’ and ‘B’ whose boiling points differ by 5°C can be separated by which process ?
Answer.
Fractional distillation.
Question 26. What is an aqueous solution ?
Answer.
A solution in which water is solvent is called an aqueous solution.
Question 27. Why sky appears blue ?
Answer.
The blue colour of sky is due to scattering of light by fine dust particles which are present in the atmosphere.
Question 28. Which of the following are colloidal solutions ?
(i) Common salt solution
(ii) Starch solution
(iii) Haemoglobins
(iv) Milk
Answer.
Except common salt solution, all are colloidal solutions.
Question 29. What is coagulation ?
Answer.
The process of converting a colloidal solution into precipitate is called coagulation.
Question 30. What is emulsification ?
Answer.
The process of making an emulsion from an oil is termed as emulsification
Question 31. Which substance is used to stop bleeding from a fresh cut ?
Answer.
Alum or Ferric chloride?