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प्रश्न
Give reasons
Graphite is used in the leads of pencils
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उत्तर
Graphite turns paper black that is why it is used in the leads of pencils.
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संबंधित प्रश्न
Give reasons for the following.
Sodium and potassium are stored in kerosene.
Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down word equations of all the reactions taking place in this process.
Give a reason for the following:
Alkali metals are good reducing agents.
Give the composition of an alloy called solder. State its one property and one use.
The alloy in which one of the metals is mercury is called an ______.
Name one ore of manganese. Which compound of manganese is present in this ore? Also write its chemical formula.
Take an element from an alkali metal and one from an alkaline earth metal and write an equation for their action with:
Hydrochloric acid,
When a copper coin is dipped in silver nitrate solution, a glitter appears on the coin after some time. Why does this happen? Write the chemical equation.
What is it made from? Why?
Pots and pans
With reference to the following metals state their use in daily life metal:
Lead
Give a reason why a green deposit is seen on the surface of an article of copper
Halogen reacts with acid.
Give reasons for the following.
- Aluminum foils are used to wrap food items.
- Immersion rods for heating liquids are made up of metallic substances.
- Sodium and potassium are stored in kerosene.
- Mercury is used in thermometers.
Generally, metals are solid in nature. Which one of the following metals is found in a liquid state at room temperature?
Name one metal and one non-metal that exist in liquid state at room temperature. Also name two metals having melting point less than 310 K (37°C)
Metals are usually solids or gases at room temperature.
Name two soft metals which can be cut with a knife.
Why are bells made of metals?
Match the following
| i. | Softest metal | a. | Copper |
| ii. | Hardest metal | b. | Sodium |
| iii. | Hardest non–metal | c. | Osmium |
| iv. | Ductility | d. | Diamond |
Why do metals appear shiny?
