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प्रश्न
Define the following term of Atom .
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उत्तर
Atom — An atom is the smallest part of an element that takes place in a chemical reaction.
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संबंधित प्रश्न
Gases have definite volume but no definite shape.
What is the scientific name of particles which make up mater?
The best evidence for the existence and movement of particles in liquids was provided by :
Fill in the following blanks with suitable words :
The elements which are sonorous are called ..........................
Classify the following into elements and compounds :
- H2O
- He
- Cl2
- CO
- Co
Which of the following are ‘pure substances’ ?
Ice, Milk, Iron, Hydrochloric acid, Calcium oxide, Mercury, Brick, Wood, Air
State two physical properties on the basis of which metals can be distinguished from non-metals.
Name a metal which forms amalgams.
Which of the following is not an element ?
There are three substances X, Y and Z. The substance X does not have a fixed melting point or boiling point and it still shows the individual properties of its constituents. The substance Y is a pure substance which occurs in nature as such. The substance Y has a fixed melting point and boiling point but it cannot be broken down into simpler substances by any chemical means. The substance Z is also a pure substance whose properties are entirely different from those of its constituents. The substance Z can, however, be divided by electrolysis into two substances which belong to the same class of substances as Y.
- What type of substance could X be ? Name one substance like X.
- What type of substance could Y be ? Name one substance like Y.
- What type of substance could Z be ? Name one substance like Z.
- Which process involves absorption or release of an appreciable amount of energy : formation of substance X or formation of substance Z ?
- Name the three groups into which all the substances like Y are divided on the basis of their properties.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
How is the impurity of iron present in several substances removed in industries ?
How will you separate iron pins from sand ?
Which method is better for recovering sugar from sugar solution : evaporation or crystallisation ? Give reason
for your answer.
How can you obtain pure water from a salt-water mixture (or salt-solution) ? Draw a neat and labelled diagram of the apparatus you would use to obtain pure water from a salt-water mixture (or salt-solution).
Draw a labelled diagram of the fractional distillation apparatus used for separating a mixture of alcohol and water.
Matter is made up of ______.
Which of the following are homogeneous in nature?
(i) ice
(ii) wood
(iii) soil
(iv) air
Complete the following table:
| S.No. | CELSIUS | KELVIN |
| 1. | 90°C | 363 K |
| 2. | ______ | 283 K |
| 3. | 63 °C | ______ |
| 4. | 250°C | ______ |
| 5. | ______ | 303 K |
Define the term matter.
