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प्रश्न
Give the formulae of the compounds formed from the following sets of elements :
- calcium and fluorine
- hydrogen and sulphur
- nitrogen and hydrogen
- carbon and chlorine
- sodium and oxygen
- carbon and oxygen
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उत्तर
- Compound formed with calcium and fluorine will have the chemical formula CaF2. (valency of Ca is 2 and that of F is 1)
- Compound formed with hydrogen and sulphur will have the chemical formula H2S. (valency of S is 2 and that of H is 1)
- Compound formed with nitrogen and hydrogen will have the chemical formula NH3. (valency of N is 3 and that of H is 1)
- Compound formed with carbon and chlorine will have the chemical formula CCl4. (valency of C is 4 and that of Cl is 1)
- Compound formed with sodium and oxygen will have the chemical formula Na2O. (valency of Na is 1 and that of O is 2)
- Compound formed with carbon and oxygen will have the chemical formula CO2. (valency of C is 4 and that of O is 2, divided by the common factor of 2)
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संबंधित प्रश्न
What is meant by the symbol of an element ? Explain with examples.
The atomicities of ozone, sulphur, phosphorus and argon are respectively :
The formula of a compound is X3Y. The valencies of elements X and Y will be respectively :
The formula of carbonate of a metal M is M2CO3.
What will be the formula of its phosphate ?
Match the following:
| Column A | Column B |
| (a) Pb(NO3)2 | (i) rotten eggs smell |
| (b) CO2 | (ii) burns with a pop sound |
| (c) (NH4)2Cr2O7 | (iii) the suffocating smell of sulphur |
| (d) HCI | (iv) lime water turns milky |
| (e) NO2 | (v) crackling sound |
| (f) O2 | (vi) residue swells up |
| (g) H2 | (vii) brown gas |
| (i) H2S | (viii) supports combustion |
| (j) SO2 | (ix) fumes with NH3 solution |
Write the formula of the following compound:
Calcium chloride
Write the formula of the following compound:
Zinc oxide
Write the formula of the following compound:
Copper [II] nitrate
Write the formula of the following compound:
Lead [II] chloride
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.
