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प्रश्न
Explain why, hydrogen and oxygen are considered elements whereas water is not considered an element.
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उत्तर
Hydrogen and oxygen are considered as elements because they cannot be split further into simpler substances by usual chemical methods as they are made of one kind of atoms. On the other hand, water is not an element, as it consists of different types of atoms, i.e., hydrogen and oxygen and can be split up into its components by chemical processes.
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संबंधित प्रश्न
Solids have definite shape and definite volume.
Define matter.
Which of the following materials fall in the category of a “pure substance”?
- Ice
- Milk
- Iron
- Hydrochloric Acid
- Calcium oxide
- Mercury
- Brick
- Wood
- Air
When extremely small particles X derived from the anther of a flower were suspended in a liquid Y and observed through a microscope, it was found that the particles X were moving throughout the liquid Y in a very zig-zag way. It was also observed that warmer the liquid Y, faster the particles X moved on its surface.
- What could particles X be ?
- What do you think liquid Y is ?
- What is the zig-zag movement of X known as ?
- What is causing the zig-zag movement of particles X ?
- Name the scientist who discovered this phenomenon.
- What does this experiment tell us about the nature of liquid Y?
Which of the following is a mixture ?
Salt, Air, Water, Alum, Sugar
Fill in the following blanks with suitable words :
An element is made up of only one kind of ........
What are the two types of pure substances? Give one example of each type.
Give reason why copper metal is used for making electric wires.
One of the following liquids will leave behind a residue on heating. This one is :
How will you separate a mixture of iron filings and powdered carbon ?
How is the impurity of iron present in several substances removed in industries ?
One of the following does not undergo sublimation. This one is :
Which one of the following scrap metal cannot be separated by magnetic separation ?
A solid mixture contains four constituents P, Q, R and S. P consists of tiny grains and it is mixed with
cement for plastering the walls. Q is a white solid which is recovered on a large scale from sea water by the
process of evaporation. R is in the form of tiny particles of a material whose corrosion is called rusting. And
S is a white solid which is used in making ordinary dry cells.
- What could P, Q, R and S be ?
- How would you separate a mixture containing P, Q, R and S ?
The given mixture contains three constituents A, B and C. The constituent A is a yellow coloured, solid element which dissolves in a liquid D. The constituent B is a blue coloured salt which is insoluble in liquid D but dissolves easily in another liquid E. The constitudent C is a liquid which is used in cooking food and forms a solid fat on hydrogenation.
(a) What do you think could (i) constituent A, and (ii) liquid D be ?
(b) What could (i) constituent B, and (ii) liquid E be ?
(c) What could liquid C be ?
(d) How will you separate the mixture containing A, B and C ?
Name the metals that are used in jewellery.
Diffentiate between absorption and adsorption.
______ is a smallest particle.
______ is used for industrial refrigeration and transporting frozen food.
Define the term matter.
