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प्रश्न
Which of the following are ‘pure substances’ ?
Ice, Milk, Iron, Hydrochloric acid, Calcium oxide, Mercury, Brick, Wood, Air
उत्तर
Iron and mercury are pure substances because these are elements. Hydrochloric acid, calcium oxide, and ice are also pure substances, as they are compounds.
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संबंधित प्रश्न
Which of the following materials fall in the category of a “pure substance”?
- Ice
- Milk
- Iron
- Hydrochloric Acid
- Calcium oxide
- Mercury
- Brick
- Wood
- Air
What is the scientific name of particles which make up mater?
When a gas jar containing air is inverted over a gas jar containing bromine vapour, the red-brown bromine vapour diffuse into air. Explain how bromine vapour diffuse into air.
When a crystal of potassium permanganate is placed at the bottom of water in a beaker, the water in the whole beaker turns purple on its own, even without stirring. This is an example of :
Name a non-metal which is a good conductor of electricity.
What is meant by saying that metals are malleable and ductile ?
Which of the following are compounds ?
- CO
- No
- NO
- Co
On the basis of composition of matter, milk is considered to be :
Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evolved and when dilute hydrochloric acid was added to part B then gas E was evolved.
- What type of substance is B ?
- What type of substance is C ?
- Name the gas (i) D, and (ii) E ?
- State one characteristic property of gas D.
- Write one test to identify gas E.
Calculate the concentration of a solution which contains 2.5 g of salt dissolved in 50 g of water.
Explain what happens when a beam of light is passed through a colloidal solution.
One of the following liquids will leave behind a residue on heating. This one is :
100 mL of water at room temperature of 25°C is taken in a beaker and a little of solid S is dissolved in it by stirring to obtain a solution X. More and more of solid S is added to the solution with constant stirring, while keeping the temperature of solution constant at 30°C. After some time it is observed that no more solid dissolves in water and at the same time some solid is also left undissolved at the bottom of the beaker.
- The contents of beaker are filtered through a filter paper to obtain solution Y in the form of a filtrate.
- What name is given to solutions like X ?
- What name is given to solutions like Y ?
- What will you observe if the solution Y at 30°C is cooled down to 10°C by keeping the beaker in crushed ice ? Why ?
- What term is used to denote the amount of solid dissolved in 100 grams of water in a solution lie Y ?
Name the process which can be used to purify an impure sample of copper sulphate.
Fill in the following blanks with suitable words :
The separation of liquids by fractional distillation is based on the difference in their .....................
All the matter made of ______.
Non-metals are usually poor conductors of heat and electricity. They are non-lustrous, non-sonorous, non-malleable and are coloured.
Name a non-metal which exists as a liquid at room temperature.
Liquids have ______.
The movement of particles in liquids is ______.
Define the term matter.
