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प्रश्न
Fill the following blanks with suitable words :
In a chemical reaction, the sum of the masses of the reactants and the products remains unchanged. This is called ....................
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उत्तर
In a chemical reaction, the sum of masses of the reactants and their products remain unchanged. This is called the law of conservation of mass.
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संबंधित प्रश्न
An element A forms an oxide A2O5.
What will be the formula of chloride of A ?
Name the element in the compound and give the formula of the following compound:
Blue vitriol
Write the formula of the following compound:
Magnesium carbonate
Write the formula of the following compound:
Iron [III] oxide
State of the following formula of a compound is incorrect. Incorrectly write the correct formula.
NaZnO2
Find the valency of the element which is underlined in the following formula.
- NaCl
- CO2
- Al (PO4)
- Ba (NO3)2
- CaCl2
Write the molecular formulae of all the compounds that can be formed by the combination of the following ions
Cu2+, Na+, Fe3+, C1– , `"SO"_4^-2`, `"PO"_4^3-`
Play a game for writing formula.
Example 1: Make placards with symbols and valencies of the elements separately. Each student should hold two placards, one with the symbol in the right hand and the other with the valency in the left hand. Keeping the symbols in place, students should criss-cross their valencies to form the formula of a compound.
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.
