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प्रश्न
State of the following formula of a compound is incorrect. Incorrectly write the correct formula.
Ca2(PO4)3
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उत्तर
Ca2(PO4)3
Correct formula – Ca3(PO4)2
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संबंधित प्रश्न
Write down the formulae of sodium oxide.
Write down the formulae of sodium sulphide.
State the chemical symbols for the following elements :
Sodium, Potassium, Iron, Copper, Mercury, Silver.
Give the formula and valency of:
aluminium ………………. .
The formula of the nitride of a metal X is XN, state the formula of :
- its sulphate
- its hydroxide.
Write the formula of the following compound:
Potassium sulphate
Write the formula of the following compound:
Sodium nitrate
Write the formula of the following compound:
Sodium bicarbonate
Write the formula of the following compound:
Sodium iodide
Write the formula of the following compound:
Calcium chloride
Write the formula of the following compound:
Magnesium sulphate
Write the formula of the following compound:
Aluminium hydroxide
Write the formula of the following compound:
Lead [II] oxide
Write the formula of the following compound:
Lead [II] nitrate
Write the formula of the following compound:
Silver [I] chloride
What do you understand by chemical formula of a compound? What is its significance?
Write the molecular formulae for the following compounds
Mercury (II) chloride
Complete the following crossword puzzle (Fig. 3.1) by using the name of the chemical elements. Use the data given in Table.
| Across | Down | ||
| 2 | The element used by Rutherford during his α–scattering experiment | 1 | A white lustrous metal used for making ornaments and which tends to get tarnished black in the presence of moist air |
| 3 | An element which forms rust on exposure to moist air | 4 | Both brass and bronze are alloys of the element |
| 5 | A very reactive non–metal stored under water | 6 | The metal which exists in the liquid state at room temperature |
| 6 | Zinc metal when treated with dilute hydrochloric acid produces a gas of this element which when tested with burning splinter produces a pop sound. | 8 | An element with symbol Pb |
Play a game for writing formula.
Example 2: A low-cost model for writing formulae: Take empty blister packs of medicines. Cut them in groups according to the valency of the element, as shown in the figure. Now, you can make formulae by fixing one type of ion into other.
For example:
The formula for sodium sulphate:
2 sodium ions can be fixed on one sulphate ion.
Hence, the formula will be Na2SO4.
Do it yourself:
Now, write the formula of sodium phosphate.
